I'd just like to point you to this here link:
http://www.uesp.net/wiki/Oblivion:Gripes
This should cover most of the flaws of Oblivion, I believe.
Oh, and by the way, I've seen the Radiant AI at work, and it doesn't look very "radiant"... Atleast, I don't think people standing in the middle of the road staring straight ahead at some far-away wall is very "radiant"...