IWD2 lacks a certain something. Let me put it this way: I played IWD 3 times, but for IWD 2, I felt that once was enough. The thought of playing it again frankly fills me with uncertain dread. Maybe it's the uninspiring plotline. Maybe it's the fact that most combat consists of: as many enemies as possible to fill the monitor swarming over you. IWD2 has its charms and good moments, but for the most part, it's not all that great. 3e rules are implemented far better than they are in NWN, though, this is certain.
BG1 has way, way too many "empty" areas. You know, areas where there are some monsters sprinkled, a meaningless NPC or two, and very little else. Space-fillers that aren't worth the time exploring. The NPCs lack personality and interaction the likes with which players of BG2 are familiar. The gameplay is limited due to the low level restriction. The story was quite okay, though. But I couldn't force myself to play it again, either.