Although I loved Dragon Age, I have to say that I didn't really find the AI that much of an improvement.
I had so many times that I lost battles, and wanted to scream at the screen because my party members did brain dead things like stand there not hitting anything, and I didn't find out until I cycled back to them from controlling another character, and realized they were cheerleading from the sidelines.
Or, better yet, after pausing to hand out orders, to resume the game, concentrating one one character like Morrigan, and having her cast Blizzard on a group of four opponents standing at a distance, and then assigning the rest of my group to handle a smaller group of nearby opponents outside the Blizzard......and then notice that Leliana's health is suddenly plummeting, and find out that she's moved herself out of backstab position on the opponent I assigned her to, and crossed the darn screen on herself, into the effect of the Blizzard spell, where she's getting whacked by the spell, and the four opponents she's allowed herself to get surrounded by.
The game did that kind of thing incessantly, and it was a collossal pain in the butt.
I still loved the game....and in many respects I like it better than NWN...but, I feel that, as pointed out by someone else, The Witcher was the better game of the three.
I'd rank it:
Witcher
Dragon Age
Neverwinter Nights 2
Sincerely,
Banshee