I'm 99% sure I'll be downvoted as an original fanboy, but here's my take.
PvP - Builds are non-existent, at least if you're not using the agape ring, which also causes balance issues at high SM. Lack of Red Eye Orb makes it more difficult to get invasions, you have to either go to NG+ and spend 10k for each invasion or farm them. PvP in general is slower paced, with absolutely horrible hitboxes, don't get me wrong the original had it to (yay lagstabs) but they're much worse in the second game. Weapons seem less unique to me, as many of them have very similar movesets, and just aren't as interesting. That's all I can think of right now.
PvE - Super annoying tracking on a lot of the enemies, like they're spinning around on a turntable to hit you. Very linear, boring areas. World doesn't have the sense of coherency that the original has. Boring NPCs/NPC storylines. Super annoying NPC invaders, particularly in the DLC (though I heard SotFS fixed that). Also the original Dark Souls map is much more open and less linear, so that you have a lot more options on what to do (For instance: Sprinting to Vamos to get a Fire weapon at the very beginning of the game).
Dark Souls 2 did do some things better though. Rolling is no longer 4-directional when locked on AFAIK, and strafing is slower so there's no Circle-Stabbing. Personally I found Circle-Stabbing to be fine, it made you have to watch your back, but I know a lot of people didn't like it.
As a final thought remember that these are my opinions, and if you're looking for more of a critical view, post on /r/darksouls, since they are the ones liking the original game. Also here is a good video called "Dark Souls 2 Critique". It's about 45minutes long so it's a big video, but I easily watched through all of it when I first saw it, without even meaning to. I'm sure there's a lot of biased opinions in there, but it's still relevant to your question. In my personal opinion, both are pretty darn good games, but the original is miles better. I do like the /r/darksouls2 subreddit a lot more though, mostly because it's better content, rather than 30% fanart, 30% sappy "how dark souls changed my life" posts, and what ever else.
Sorry if y'all disagree with me but it's what I think. Thanks for reading I guess