Made it to Seek's Castle/Palace/Library/Whatever after killing the Bed of Chaos and getting my Chaos Flame Great Scythe to +3 and Chaos Blade to +4 now (Which BTW, Annihilated the Firesage Demon).
The more I play the more I find bosses and little design decisions that I don't particularly like. Though I'm referring mostly to bosses. There's a couple things that I really hate like that Bonfire in Darkroot Basin (you know the one, we all know the one) and little moments where you're just trying to reach a spot and you rolled or you ran or you leaped from a slightly different angle and the geography was deigned in such a way where if you didn't make the perfect leap you get pushed off.
A lot of bosses I don't generally like or there's a flaw there that DS2 doesn't really have:
Bed of Chaos sucks. Just flat out sucks. Horrible boss fight. Cool idea but badly implemented.
Flame Centipede (Whatever his name is). You're not given enough room to fight him unless you cut off Ceasless' tail and that's incredibly difficult and is something that you need a partner to help you with. So you basically have to cheese him on a very small spot of land and if you target him the camera goes nuts. So not a good idea to target.
Belfry Gargoyles. I actually like this fight but I hate the camera when you're targeting. If you're targeting one of them, and then that one flies into the air, the camera assumes this insanely close position to your character and it looks up at the Gargoyle. This is a huge problem when you have to deal with the other one and also trying to stay away from the edge of the roof. So you basically have to untarget, take a moment to re-orient yourself, then run away and get good in a good position and re-target one of them.
Ceasless Discharge. I hate his pattern. I hate the retarded damage he does. The easy way to kill him is cute but it's still a lame fight.
Capra Demon. Again, the camera/targeting system ruins it because the environment you fight him in is so small and you're prone to get really close to him so the camera (again) gets way too close and it's difficult to see.
Gravelord Nito. Assume you did not know the trick in "Hugging" him and just keeping close and using a halberd kind of weapon. How the hell are expected to beat this dude? That homing attack is complete BS and you have to fight him in an enclosed space or you aggro Giant Skeletons. And the skeletons infinitely respawn until you kill him. AND you take fall damage when you jump in there. AND when you drop down sometimes he does that homing attack right away and sometimes he doesn't.
Duke's Dear Freja, Looking Glass Knight (with Player summons in NG+), Skeleton Lords, Throne Watcher and Defender, the Gank Squad, the King's pets are while technically harder there's no way to cheese them other than playing offline against Looking Glass Knight. If being played legitimately without using the "Hugging" trick Gravelord Nito is easily harder than all of the DS2 bosses I mentioned.
DS1 has generally better designed bosses but I feel like DS2's were a lot more fun to fight and I experienced far fewer janky problems with them.