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: Donkey Kong 64
Awesome Music: Frantic Factory, Fungi Forest, King Kut-Out, and Hideout Helm. Props also go to the boss intro theme.
Breather Boss: Army Dillo in Crystal Caves, he's almost the same as in Jungle Japes except you have three melons now, making him a bit easier in that regard. The only upgrades he has are the jet pack and heat seeking missile. Despite that, he's only a smidge harder than the first two bosses.
Good Bad Bug: Using Lanky's arm stretching move, you can enter worlds with B.LOCKER on them, allowing you to access worlds you don't have enough golden bananas for.
The last Banana Fairy to be photographed is in the final room, and is nearly impossible to capture on film since due to her frantic flying. However, she only flies about when you're actually in the room, and you can take her picture through a window with no trouble at all. It's unclear if this is actually a glitch or a treat for thinking outside the box.
Scrappy Mechanic: Beaver Bother. It's a basic herding game where, as a Klaptrap, you have one minute to scare Gnawtys into a tiny hole in the center of a round stage. Problem is, the collision detection for the beavers vs. the hole is a little too good, and your Klaptrap can't simply push them in, also due to collision mechanics. The Gnawtys also have a slowish respawn, and frequently get stuck on the wall. There's one game that requires you to herd 12 Gnawtys in the hole, which is difficult, but then there are two, count 'em: TWO, versions that require you to herd 15.
Any of the races that require you to collect a certain number of coins and still beat your opponent. In particular, the slides. It seems Rare didn't learn their lesson from Diddy Kong Racing.
The mechanical fish in Gloomy Galleon deserves a mention. You have to play Diddy's guitar on top of the lighthouse, get to the other section, dive underwater, and get into the submarine and then the fun begins. You have to shoot out all three of the lights (hit them three times to turn them from red to white to busted) but the propeller and respawning Zingers make this the last banana many players get. And that countdown timer gives you barely enough time if you do it exactly right. It's not only much tougher than Beaver Bother, but at least with Beaver Bother you can jump right in the banana barrel again, here you have to go back to the top of the lighthouse and do that all over again.
So Bad, It's Good: The DK Rap, the lyrics of which composer Grant Kirkhope has admitted were written to be deliberately cheesy.
Squick: Pretty much everything about Candy Kong is this for some people.
Mad Jack. He combines this with Goddamned Boss. You're forced to twirl back and forth between platforms to avoid being smashed. Worst of all, he speeds up as the battle goes on, so you need to land precisely on the edge of every platform or else you won't have enough time to reach the next one. This repeats for 10-15 times, and if you fall off, the pattern starts over. Also the camera is known to make a switcheroo mid-twirl. The secret is to stay in the middle four platforms, but this isn't even perfect because his panels can appear anywhere. Another trick is to jump off the edge and stay on the platform that raises you up until he jumps up again, though this will eventually require a difficult jump as he wises up and stays on the "corner."
King Kut-Out also qualifies for some who haven't mastered the patterns in his third stage. However, King Kut-Out becomes much easier once you realize you need to shoot him when he's actually in front of you, not when you predict he will be. Once you actually see him at any of the openings, you can shoot freely; once a shot is fired he stops moving, so if he was somewhere else you'll lose a Kong, but if he was right in front of you it's a guaranteed hit.
Dogadon, the second time around. The final "form" of this boss involves him pounding the battle platform into molten lava. It's unclear exactly how much HP he has in the sections where you need to get big with Chunky and punch him. Chunky's stronger moves seem to be less effective than using his neutral B move over and over and over again, though repeatedly using his charge-up punch does the trick too.
How about the Gloomy Galleon boss, Puftoss? To damage the boss, you have to pilot a little motorboat through a series of checkpoints. The problem is, it handles about as well as the hovercraft in Diddy Kong Racing, and the checkpoints get smaller and smaller. The first phase is deceptively easy, but then it gets cruel. In the second phase the checkpoints are still as large as the first time where it's easy, but it becomes hard because they're all next to him and he spams you with shockwaves that stun you. In the third phase, the stars vary from close to far as they will in the last three. His shockwaves are less frequent thankfully, and disappear in the fourth and are replaced by heat seeking missiles that do half a melon's worth of damage (still better than one hit kill). Fifth stage of the battle near the end can be either almost impossible or easy, depending on if you have enough health left to take one or two hits since the star reappears in the same location.
That One Level: Crystal Caves, at least until you kill the guy bringing the ceiling down on your head. Many golden bananas are also difficult to get, leading to a difficulty spike.
Crystal Caves also has that spinning maze which you have to complete at a fixed camera angle, slices a whole melon from your health meter if you touch the wall, and gives DK only a marginal amount of space to move around in.
Also, contrary to Super Mario 64, either of the slides. Even in Angry Aztec, which is overall an easy level.
The arcade Donkey Kong game in Frantic Factory. It has to be beaten twice in order to reach the final boss, but you have to beat the entire game with one life both times. If you can get ten thousand points (reasonably easy in the second round), you can get another, but that's a small consolation when playing a game where the average player's lifespan, according to The King of Kong, is thirty seconds.
It's made even more annoying by the fact that you get sent back to the factory when you lose, and go through the whole cinematic of DK grabbing the lever and the title screen before you can try it again.
If you use the D-pad instead of the analog stick, it tightens up the controls a lot and makes things somewhat easier. Where is this hinted at? Nowhere!!
The Woobie: K. Lumsy. Trapped in a cage where he can't even sit down and all because he refused to destroy DK isles.
The Banana Fairy Queen. When you first meet her, she's crying because her Banana Fairies ran away.