The ending wasn't what I expected either.
Yeah the ending really threw me the first time through. Felt a little railroaded when I imagined my character's story going a wildly different way. There was still a slight out, but I think there really needs to be a few more options and polish to Act 3 in general.
Still enjoy all the acts. Still a great game and probably GotY, probably the best CRPG I've ever played, but I felt like I had my orgasm denied in a few places that it seemed like just a little bit more content, reactivity and player agency would have solidified the game.