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.
Gnarl: This is why survival of the fluffiest has never caught on, Sire. They're just too stupid.
Ear Worm: The opening music. Easy to sing along to, as well.
Even Better/Surprisingly Improved Sequel: Outside of the obvious graphical touch ups, the melee attacks are more meaty, the plot is arguably better, you're not just limited to one mistress (you can even get with all three if you play your cards right), the mounts add to the gameplay, and there's no "good" alignment (just Lawful Evil or Chaotic Evil).
That One Boss: The Boss Battle against the Spider Queen is this. Figuring out how the fight even works at first can stump newcomers for awhile, and the fight is well-known to drag depending on how well the player keeps an equipped team of Minions alive. Not to mention the repetitive nature of the fight by always having to flip the Queen over as the only means to inflict actual damage on her.
Any of the catapult levels. Catapults aim like ass, take a long time to windup and once fired the camera follows the rock until it lands, during which time the game will still be going, so your target will just move out of the way, requiring re-aiming.
Traversing the wall-maze with the spider mounted green minions to work the Spider Queen's elevator rubs A LOT of people the wrong way. Much harder for PC users due to the game being developed around consoles where the controls are already quite frustrating.
The prime offender being the 1000 gnome genocide Side Quest if you can stomach the patience to continuously mutilate the little guys. It gets worse when you start encountering the gnomes that actually FIGHT BACK!
Another good candidate is the 100 civilian enslavement Side Quest for Everlight. It seems simple at first, but you soon realize that you can't complete the mission in one go, because a portion of the town is closed off until you can activate the Elf Rebellion Side Quest later on. These elves however, all count towards the 100 civilians for the previous mentioned quest so completing the elf rebellion while also trying to keep the elf rebellers alive to complete the civilian enslavement quest can be quite a struggle, because the roadblocks you come across during the Elf Rebellion quest always seems to get one or two elves unintentionally killed; forcing a restart for the level.
They Changed It, Now It Sucks: The Overlord's drastic decrease in spells compared to the amount of spells found in the first game. The lack of spell variety for the player/Overlord was greatly missed.
Almost everyone agrees that the Wolf mounts are miles ahead of the Spider and Salamander mounts in utility, and are considered to be the best choice for the final battle.
Salamanders form the middle ground where they make the Red Minions forces to be reckoned with, but require the most micro work to reap the benefits.
The Spider mounts come off as the worst where they seem to not benefit greatly to the Green Minions role in assassination and suffer from very odd wall-climbing mechanics that are universally hated amongst the players. They are considered the worst choice for the final battle.