These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
Angst? What Angst?: At the end of the story, Riku passes the exam and is recognized as a Keyblade Master. Sora failed the exam when darkness seeped into his heart but he remained optimistic and set out soon after to do his own thing.
Word of God says that Vanitas was an image conjured up by Ven's heart reacting to Xehanort, and wasn't really there. As for the Riku Replica, rampant speculation is that he's one of the thirteen Seekers of Darkness.
Maleficent and Pete's appearance. They show up, are driven away by Lea, and the plot carries on without further mention of them.
Broken Base: Lea getting a Keyblade, time travel, and the revelation that Nobodies can grow hearts have had mixed reactions.
The whole game breaks the base, mainly due to amping up the Mind Screw and Kudzu Plot like never before. This is either seen as a turn-off or an attraction. Also, because it generated so much hype prior to release, it has the problems of having dizzying expectations to live up to, and the base is further broken as it matches some while fails to with others.
The new remix of "Calling" is pretty Love It or Hate It, mainly because of the vocals compared to the original.
Catharsis Factor: All of the Xehanort fights. Master Xehanort still has not truly paid for his horrible crimes from both Birth By Sleep and this game, but bludgeoning his alternate selves with a giant key, powerful commands, and Flowmotion certainly helps—even if they all survive the battles seemingly no worse for wear.
Continuity Lockout: Surprisingly, the developers consciously attempted to avert a lockout for new players. Whenever Continuity Lockout would otherwise rear its head, a new Chronicle summarizing a previous game is unlocked in the Mementos menu. Considering the nature of the game in terms of continuity, the complexity of the story and the many plotlines it encompasses, this was a very good idea; whether it was a successful one or not varies from player to player.
Crowning Music of Awesome: Special mention goes to "Le Sanctuaire", considered one of the best standard battle themes the series has to offer alongside "Byte Bashing", "Scherzo di Notte", and "Fragments of Sorrow".
Demonic Spiders: In the later part of the game, Aura Lions and Keeba Tigers. They constantly spew copies of themselves that block your hits and home in on you, they have a good chunk of HP, and worst of all, they can randomly decide to become invulnerable while they jump and dive into the ground, damaging anyone on impact, and reappearing who knows where a second later. And of course, they will almost always do this last one right when you're about to hit with one of your big Commands that takes a lot of charge time. But wait, there's more! One of Riku's Special Portals is against three Aura Lions...in a small corridor with slow-moving laser beams that block your attacks and damage you but not them. If you're currently under Risky Winds, you can literally spend an entire turn with Riku and fail to kill all three before Dropping.
The Aura Lion and Keeba Tiger are also popular, with many players using them on their teams just for the "cool" factor. One can also say this about Tyranto Rex, which is one of the biggest, most useful and most Badass-looking Spirits you can have in your party.
When it comes to the worlds featured in the game, The Grid seems to get the most love from fans, despite the Light Cycle challenge and the boss battle with Rinzler. It helps that it's predecessor world, Space Paranoids, is also popular with fans, especially in Japan.
Flowmotion grants you fast dashes, high jumps, and powerful attacks, and most enemies will have difficulty hitting you. The only limit is having a rail or a wall to jump off of. Around the middle of the game, provided you know what you're doing, you'll begin to get access to commands that are more powerful and/or useful than Flowmotion attacks, lessening their gamebreaker status a bit, especially since caps on how much damage you do to bosses seem to have been lessened or done away with. Flowmotion Attacks are still good on their own though, which will help you early-game.
The thing with the Flowmotion moves is that they don't deal out very much damage. However they are fast, have very large range, can home in on enemies over very long distances, can not be interrupted, have no cost, and move you out of the way very quickly, all at the same time. And they either have lots of invincibility frames or make your hit-box smaller, because some point blank moves will go right through you while you're performing them. You can take damage during them, in which case you have no way to avoid it, but that doesn't happen often enough to make it dangerous.
Another thing about Flowmotion is that you have all the moves from the very beginning of the game and there are only about a half dozen or so actual Flowmotion attacks. So they quickly fall into Boring but Practical territory. While that doesn't take away from the Game Breaker status, it does make them less likely to be exploited.
Flowmotion also makes the existance of KH's standard movement abilities (Air dash, high/double jump, glide)in Dream Drop Distance pretty much completely pointless, as Flowmotion can do all that those abilities can do plus more... Or it would if it weren't for the fact that using Flowmotion is restricted to how many walls and other context-sensitive objects you can use, as well as the fact that you're not able to use normal commands while in Flowmotion state, Superglide is arguably just as good as using Flowmotion, and Doubleflight allows you to pull of normal commands like Meteor Crash and Curaga.
The Balloon series of spells.
Especially Balloonga. It can be obtained fairly early in the game, can be activated almost instantly, and can throw foes into the air with six balloon-tracking... balloons to explode on their faces. The spell can also be used as a floating mine. Hilariously enough, this spell is also pretty useful in Flick Rush itself.
Once Riku gets his Dark Barrier, and the counterattack associated to it, well-timed use of it allows Riku to be virtually invincible and dish out damages at the same time. It even works against bosses (though some of end-game ones will wait for an opening and punish you if you try to spam it).
A Riku-exclusive command, Dark Splicer, makes you a player character with a Teleport Spam technique. It hits hard and is a very long combo, and besides just being strong, it can completely destroy the strategy behind the second Ansem battle. The one drawback is that you can take damage during it, but having Curaga at the ready mitigates this for the most part.
Another Riku-exclusive command, is as useful as (or even more than) Dark Splicer: DarkAura, Riku's Signature Move, now available as a mere 2-slot command! Given how it's That One Attack in several KH games with Riku as a boss, it was to be expected.
Riku gets a lot of commands that break the game in favour of him, actually: Meteor Crash is really good for chipping off damage on large bosses, or clearing groups of Mooks, and can be combined with Doubleflight to pull it off in a relatively safe manner. Dark Firaga splits into multiple balls of darkness which all do decent damage, and it can be used at range, making it another great boss killer. Dark Roll has more invincibility frames than Dodge Roll (which was nerfed in this game), and Dark Barrier is pretty much Aqua's normal Barrier move with a dark twist on it. The aforementioned Doubleflight itself can be used to pull of your long-charging commands safely, or to make it easier to get off a Cure spell. Finally, Shadow Slide lets you Flash Step behind the enemy where using the follow-up move Shadow Strike allows Riku to pull of a combo during which he's invincible to attacks (it's much better than Ventus' or Aqua's equivalents).
Goddamned Boss: Holey Moley is not that dangerous a boss, but landing a hit can be a challenge, as he keeps warping around the large, obstacle-filled room.
The Recusant's Sigil, which as explained on the Fridge page for the game has been around in subtle forms since the start of the series. Tetsuya Nomura found a way to justify in-universe why characters have "X" motifs and meaningless belts and straps on their clothing so often.
KH3D features Mons as party members, which naturally drew comparisons to Pokémon, one of the major aspects of this game's Mons was that it had a virtual pet aspect similar to Nintendogs for you to bond with them. It was rather amusing that little more than a year later, Pokémon X and Y was released, with introduced the Pokémon-Amie feature, which allows the player to bond with their Pokémon.
Ho Yay: When Riku first arrives at Traverse Town, the cutscene with his first meeting with Joshua ends with Riku approaching Joshua and saying "I'll help you" while the camera pans up in order to show the animation for the new Traverse Town logo. It wouldn't be so bad by itself, but sadly said animation begins with fireworks. Add Joshua's perceived "Ambiguously Gay" status from the game he's from and you get the picture.
In addition, his English voice actor does not help this situation. At all.
When Sora meets Neku, their conversation eventually turns to Joshua, of whom Neku remarks "He's my...friend." The way he says makes it seem like Joshua is a bit more than just his...friend.
There's also the Court of Miracles, home of all the gypsies in Paris. Once you get there, however, the only gypsy to be found is Esmeralda. Actually, she seems to be the only gypsy in Paris, making Frollo's speeches about how evil gypsies are even more Narmy.
Sora's voice in the English version. Haley Joel Osment is unquestionably an adult now, so hearing an adult voice come out of 16-year old Sora's mouth is both kind of disturbing and pretty hilarious at the same time.
If that's the case for the English version, then the Japanese is just as guilty, since Miyu Irino, just like he did in Re:coded, tries a little too hard to sound like he's fifteen and just sounds very inconsistent.
Sora makes some... interesting facial expressions while being implanted with Roxas' memories.
Nightmare Fuel: The giant clown face in Windup Way at the Prankster's Paradise world. The eyes actually follow you.
There's also Sora's dreams in the World That Never Was. Not only does the poor kid have no idea what's going on, the players get punched in the gut over and over by the sight of Terra and Aqua/Riku and Kairi turning their backs on Sora-turned-Ven, Namine looking regretful, having Xion outright run from Sora in presumed shame, and seeing Roxas transfer his memories to Sora. And that's not going into the Break the Cutie run Sora gets throughout this that culminates in him falling into darkness and almost (presumably) dying.
Scrappy Mechanic: The Drop mechanic is viewed as irritating and somewhat pointless by quite a few critics. It can even happen during boss battles, and when you Drop back to that battle, it'll start over from the beginning with the boss at full health. Considering the game's difficulty, this can be extremely frustrating. The mechanic does have some saving graces—if you're stuck with useless commands or need a boost, you can simply wait out the boss battle and then grind for DP to buy attack boosts, et cetera or switch out commands as the other character.
The way the game handles abilities is by far the worst out of any KH game when it comes to maxing out Spirits if you don't like caring for them: you need several thousand LP to max out most of them, killing any enemy regardless of strenght is only worth a single LP and playing minigames or feeding them isn't much faster and quickly uses up your munny reserves as well. Combine this with the fact that you also need to change each Spirit to each of their 4 possible dispositions at least once to unlock their entire Link Board which has a large random element and adds another 5-15 minutes of tapping the touch screen to the progress and you can see why completionists can easily grow tired of the damn things.
Sidetracked by the Gold Saucer: This can easily happen with the "Spirits" menu for taking care of your Dream Eaters, since it's essentially a fully functional virtual pet simulator.
That One Boss: Young Master Xehanort. He's fast, hits hard, has a lot of HP and can rewind time to the beginning of the battle when he hits 0 HP. The only way to defeat him is to use a Reality Shift on the clock that appears when he rewinds time and destroy it from the inside; however, you still have to keep him at bay whilst doing this, and the clock has as much HP as he does. If you don't do it in time, he simply rewinds time to the beginning of the battle and you have to start over again. His nickname of Trollanort is more than deserved.
Mercifully, if he does rewind time, the clock does not recover any health, and his maximum HP is reduced to whatever the clock's remaining HP is.
Same can go for Clu, especially those who finally want to get some sweet payback for his crimes in both film and game canon.
Ugly Cute: To an extent with the Dream Eaters; Nomura designed them to be appealing to the player, but not in the conventional sense of "cute and cuddly." The result is creatures like Meow Wow, who are decidedly odd-looking but still endearing in their own way.
Uncanny Valley: The Grid had Sam, Flynn, and Quorra from Tron: Legacy. The faces are so realistic it's really creepy, especially when they share a shot with Riku and Sora who have kept their stylized faces. It's comparable to the Pirates of the Caribbean situation in the second game.
Villain Sue: Xehanort may slip into this for some fans with the twists in the ending. Namely that EVERYTHING that has happened in the previous games was all part of his plan....somehow, and just how thoroughly he outclasses everyone else in the game in power and intelligence.
Woolseyism: The route the English version seems to be taking with the Dream Eater names. For example, the Japanese name "Wandanyan" incorporates "wonder", "wanwan" (a dog's bark), and "nyan-nyan" (a cat's meow). The English name is "Meow Wow", a combination of "wow", "meow", and "bow-wow."
"Dark Fierce" and "Light Hammer", became "Darkest Fears" and "Shining Hammer", respectively.
Someone was having way too much fun doing his job, because most of the Dream Eater descriptions are flat-out zany.
Lines from the Japanese script that would've been flat-out Narm (Riku's "If you're a Nightmare, I'll eat you whole!" and Sora's "This is the key to everyone's smiles" leap to mind) were given somewhat less silly translations.