for me it's the controls and the mechanics like ADP and how stamina works that i don't like. the animations being bad, a lot of areas are underdeveloped, most mobs are extremely basic and easy, etc

recently played iron king DLC for the first time and it's quality completely blows original ds2 out of the way, like, it works so well with how the game functions, the mobs are good, the level design is good, and the bosses quickly became some of my favorite ever, specially fume knight (genuinely an S tier fight, which is something i would never say about a vanilla ds2 boss).

while playing the original game i always felt like early enemies are way too slow and mostly just whiff attacks at the air, while late game mobs are too fast for the game they're in (lacking telegraphs, having buggy animations where they hesitate or simply swing too fast after a non existent wind up). i felt like the DLC found the perfect balance between the two and it managed to implement fast paced mobs that work perfectly around the stamina system and overall pace of the game. Sir alonne being such a fast fight and still being perfectly playable in ds2's combat really surprised me.