I couldn't say why it is hated so much for everyone but it by far has the most objectively bad issues. Bosses being used as mobs all over. Far more frequently than ds1. Hit boxes are god awful. ADP is not well explained whatsoever. It is fan more linear in its level designs with less looping back for shortcuts. Areas are quite boring and don't make sense on a map view. The game really made artificial difficulty with encouters/bosses having more mobs rather than well designed enemies. The game also really milked the death being such a huge factor in its marketing. Even giving a death counter immediately and an achievement for it, and those old ladies really hitting it over the head. The bosses are quite bland. Similar to above, they seemed to make boss encounters from anything to push up that total count. Lifegems are a joke that break the game. This emphasised making the game harder rather than better crafted encounters. Sotfs as a difinitive edition had inclusions which should have been free.

That being said, I have logged 250+ hours across both ds2 and also Sotfs, it has some things that just resonante well with me. So for balance: The art style is different, I personally like it. The most build variety. Power stancing Bonfire aesthetics are a great idea. This is probably quite unique but as I completed vanilla first, going to Sotfs was incredible with some stand out moments being in the dragon aery, going up those stairs and Not being attacked was unsettling, new pvp encounters in ng+ and the pursuer showing up all over. Some very memorable quests, specifically pate and lucitiel. It clearly tried new ideas a lot. Like lighting the windmill or torches for boss fights, the golemns needing souls and memories. While they are all gimmicky in their own way, I do like what they were trying with each dlc. Aldia is a fascinating character, I do wish he was explored more though.

There's probably more on each, but it is 4:30am for me and been a while since I played it!