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.
YMMV: Rhythm Heaven
Base Breaker: Let's just say there's quite a divide between fans of the original Japanese soundtracks and those of the localized soundtracks.
Breather Level: Quiz in Tengoku. Despite being one of the few mini-games to have insta-fail conditions, you don't actually need any rhythm to pass. Just do as many button inputs as the host.
Karate Man in Heaven and Fever is the last main game before you hit the credits, and it usually focuses more on being memorable than being challenging, utilizing no camera trickery, basic controls and timing, and more cues than you probably need.
Ringside in Fever, mainly as the result of being the subject of much Memetic Mutation. Since most of the parody videos are based on a perfect run, anyone familiar with the meme has the rhythm of the song memorized, making the level even easier than it would otherwise be.
Night Walk in Tengokunote Ain't it weird how the only games with insta-fail conditions are noticeably easier?. It is literally just pressing A over and over for the entire mini-game. No variation whatsoever. Thankfully, Night Walk 2 actually mixes it up with obstacles.
Ensemble Darkhorse: The Choir Kids for Heaven and Wrestler X/Reporter for Fever, with the former leading to Marshal, a Suspiciously Similar Substitute, being the mascot of Fever. The Tap Trials Girl of Tengoku, DJ Yellow of Heaven, and MC Adore of Fever are slightly lesser examples, but still incredibly popular among the fan base.
Fridge Brilliance: One of the reasons Donk Donk may be so odd compared to the other games is its rhythm—electrodes and octopi may not be inherently weirder than, say, Working Dough, but Donk Donk's rhythms are in triple time (DONK-DONK-wait DONK-DONK-wait), while almost every other game has double time rhythms (WHOA, you-GO big GUY *tap TAP*).
Hell Is That Noise: Screwing up while going for a Perfect. Not only because it means that you've burned one of your three chances for a Perfect, but also because it's loud. Thankfully, it's quieter in the Wii version.
Love It or Hate It: Not so much the games, but particular levels. Invariably, some players will latch on to certain mini-games as their favorites while others consider the same levels as the ones that frustrate them the most.
For example, in Rhythm Heaven Fever, you have Monkey Watch. Monkey Watch is the first minigame that requires the player to have a consistent rhythm throughout. Said rhythm is constantly interrupted by syncopated beats in the form of the pink monkeys. Love for this minigame seems to be split down the line between people who have a developed sense of rhythm and those or are looking to improve their rhythm. For those with a strong sense of rhythm, it is one of the first truly-involving minigames Rhythm Heaven Fever has to offer. To everybody else, it can be a complete nightmare.
Man, Suki's gonna die...note Before Fever was localized, fans of the Japanese Love Rap would choose to interpret the lyrics as a song about wanting to kill a girl named Suki, as the main song lyric is "Daisuki!"
BA-BOM BOM BOM note Forthington the cat's lob shot cue in Fever's Air Rally has proven very memorable.
Surprise Difficulty: Hey, there's cute graphics and a song consisting only of do-re-mi-fa-so. All you have to do is flick to the song to get a bolt through two pieces of metal. This is going to be a piece of cake! Of course, you'll likely still be on Built to Scale after multiple tries... And even if you blaze past the first few stages, the first remix will hit you as hard as anyWake-Up Call Boss.
In all fairness, Built to Scale pulls a particularly nasty trick on a player new to the series, since they're likely not expecting it.
For an in-game example, Samurai Slice in Heaven only needs 17 Medals to unlock, but can get more complex than Battle Of The Bands.
Awww, the seals in Flipper-Flop are so cute! Sweet, I got a medal! It's time to go for Perfec- HOW'D I MISS? Wait, the timing window for their steps is that tight?!?
Flipper-Flop isn't alone with very tight windows to maintain a Perfect run. Others include Donk-Donk and Shrimp Shuffle.
So Bad, It's Good: The English dub vocals in the songs in the DS installment, most flagrantly "Thrilling! Is This Love?".
Tear Jerker: The song for Fever Remix 8, "I Love You, My One and Only", a song about unrequited love.
Fridge Horror: Or depending on your interpretation, a relationship gone wrong:
Won't ever give you up, won't ever let go Even when you hurt me, I still love you so I'll let you take the lead, follow where you go Hear my plea, oh won't you baby
That One Boss: Remix 5 in the first game, Remix 8 in the second. Note that each rather prominently features parts from That One Level - Tengoku Remix 5 has Fireworks and its really difficult timing, whereas Tengoku Gold Remix 8 heavily features Rhythm Rally and also includes Fillbots (and its really difficult timing, especially at the speed said remix goes at) on two occasions.
To clarify the second one, once you figure out that Rhythm Rally and Dog Ninja basically go at the exact same rhythm, the beginning turns into a matter of flicking at a constant pace. It's towards the end, and the game gradually starts to speed up, that things turn sour real quick.
That One Level: Fireworks and The Bon Dance in the first game. Fillbots, Rhythm Rally, and Big Rock Finish in the second.
Try to get Perfect in Rhythm Rally 2.
Love Lizards gets a lot of flack not only because it's repetitive, but the controls tend to be over or underresponsive (depending on which one you don't want it to be).
Fever has Love Rap, which ends up comprising the last twonote (there's also Love Rap 2) medals most people get, mostly due to the rather unusual timing of the sequences (to the point where listening to the audio alone frequently produces worse results than trying to figure out the visual cues on each action). The relevant Remixes are comparably easier.
Also any part with the Tap Troupe. The major reason is that the rhythm you need to use to exit the triplet (the bounce-bounce section) is different based on how long the section lasted. You need to either end with another triplet or change to an eighth note. One particularly nasty change actually requires you to wait for about three-eighths before making the final step! Remix 7 has the same difficulty because of this.
Shrimp Shuffle is notable for two things. One is that the game counts the beats for you and it's still a pain in the crotch ("1, 2, 3! 3, 2..." *player presses button* "...1!" *miss*); the other is that when the shrimps pause, their shout of "Together!" is delayed, which doesn't actually change the rhythm - but interrupts the voice counting the beats, which makes it very easy to get confused.
Woe betide the fool who attempts to get a Perfect on Working Dough 2, which has nasty, off-beat patterns and entire sections with almost no accompanying music. And then it combines the two towards the end. Good luck with that.
Uncanny Valley: The giraffe from Tengoku's "Tap Trial", but even more so in the Feverremake. It stares towards the player throughout the entire song, without blinking or bobbing along to the music. And if you get a superb, it continues staring in the victory image.
Viewer Gender Confusion: So, is the second rocker a girl or a guy? The Try Again message for Rockers has the first rocker call the second "Guy", but for rock stars, "guy" could be a gender-neutral term.