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.
With the addition of rocket barrel levels and the removal of water levels, there's been a debate between the rocket and water levels from previous DKC games. Fortunately, water levels return in Donkey Kong Country: Tropical Freeze .
Funny Moments: Mugly's death sequence, in which it essentially does three poses before the screen before falling.
Game Breaker: The Banana Juice power-up gives you an additional ten health points on top of the existing 2 (4 with Diddy), and only costs 20 coins (it's not hard to acquire that many during a single level, and almost guaranteed across two levels). This can make some levels go from mind-shatteringly difficult to extremely easy simply by equipping it. It only lasts for one life though, unlike the Heart Boost (1 extra heart), which stays with you for an entire level no matter how many times you die (but will be removed if you exit the level). Given the game's difficulty level, the Banana Juice is almost necessary in certain situations in order to get 100% Completion. Especially in the hidden temple levels; World 5's in particular. If you were dependent on these items, then good luck trying to complete these levels in Mirror Mode, where you can't use items, Diddy is unavailable, and you only have one heart!
The groaning sound Donkey Kong makes upon dieing, in large part because you will end up hearing it A LOT.
Most Wonderful Sound: After a particularly tough level segment, nothing boosts your spirits more than the sound of a Checkpoink. Ditto the stage clear barrel fanfare.
Not to mention the sound of repeated smacks, delivered by Wiimote shakes. Whether you're smacking open an end-of-level barrel for something on the order of 15 banana coins, or saying goodbye to that world's Tiki Tak tribesman, it's always a welcome noise.
One of the forest levels has an Advancing Wall of Doom... made of SPIDERS! Even worse, they're baby spiders that come from you smashing open egg sacks. And if you fall a little too far behind they'll drag Donkey or Diddy down into their depths, complete with look of utter terror on the poor ape's face.
The aptly named "Tidal Terror". Nothing like big rogue waves coming right at the screen.
To really drive this trope home: remember Retro's last project, Metroid Prime 3: Corruption? A game that was already gorgeous? DKCR has three times as many polygons.
It could be said that most of the levels are scenery porn. It can actually be a hindrance because while you're staring at the chunks of rock slowly melting into the lava, the streams of lava pouring down from ledges, and the fireballs launching from below, you can forget that these things are there to kill you. Don't worry, the game reminds you soon enough.
The barrels that catapult you about a mile in Longshot Launch.
Seriously, nearly every level has at least one setpiece designed to show off Retro's talents.
The Scrappy: The checkpoint pig, to some frustrated players. Mostly when offering the Super Guide after countless deaths.
Scrappy Mechanic: The waggle abilities are already getting a reputation. The Ground Pound and the Blow aren't so bad. Having to waggle to do a roll (and thus perform a super jump, a key ability in the platforming) can really suck, especially if you're in a very chaotic and fast paced level.
This is largely mitigated in the 3DS port, as waggle functions have been mapped to normal button presses.
For some, the Rocket Barrel levels.
Stop Helping Me!: Once it appears, the only way to get rid of Tutorial Pig's offer to use the Super Guide is to beat the level.
The Mole Train is widely hated, because it seems to show no signs of ending and it's a matter of predicting when fighting the moles. Have fun on Mirror Mode.
Feather Fiend (the world 7 boss) can be frustrating because his pattern is hard to figure out at first and it takes awhile for him to reveal his weak point.
The final boss, as well. If you die any time during the boss battle, you don't get Diddy back. This is after a Trial and Error Gameplay-filled rocket barrel section.
That One Level: It's almost universal that Stage 4-5 is not fondly regarded. To an extent, World 4 as a whole is this.
Ugly Cute: Toothberries, the creatures first seen in Stage 3-5 and Snaggles, the sharks that leap out of the water to bite you.
Waggle: The most common complaint with the game, especially in regards to rolling.
What Do You Mean, It Wasn't Made on Drugs?: The Golden Temple. Giant, floating fruit? Alright. A bunch of floating island things? Fine. Purple, tie-wearing flying koalas that toss bombs at you? Okay, now this is weird.