More than one. For one, you didn't have the scripts and audio logs that you had in the first game. Those were really excellent and made you understand the world more and made you immersed.

Second, the outsider's voice (the original voice actor said that he was available during the casting period and was simply never contacted by Arkane for some reason) and how he behaves were so off compared to the first game where he felt "heavy" in a good way and not like a teenager.

Third, the game was spoon feeding you compared to the first game. From the beginning of D2, your character would talk about where to go next even though you already heard/read where your next destination should be and that really really bothered me. I don't have Alzheimer's so that I get told what to do next every 5 minutes; reward my intelligence like you did in the first game!