I am on my second or third playthrough. This time witha good party. Trying out new NPC combinations. And you know what? I keep finding new stuff. New (FUNNY!) interactions - between Mkhiin and Dynaheir, and Mkhiin and Corwin, for instance.
There are many new, small quests that I missed last time - found four in the past hour. New twists to quests I completed in earlier games. The quests themselves are so much more complex than the FedEx quests of BG1 and BG2. I have issues with bits and bobs (and these have been covered endlessly by other forumites), but overall it's very enjoyable indeed.
So cheers, Beamdog, you did a good job.