We went to see I, Robot at the weekend. It turned out to be better than I expected for this type of blockbuster movie (if you ignore the amazingly clumsy product placement). I thought the robots were great, looking like something designed by Jonathan Ive and, except for some of the action scenes where the CGI got a bit out of hand, fitting seamlessly into the film. I'd go so far as to say the best acting was done by the main robot, Sonny, but that may be a reflection of the rather cliched roles and shallow portrayals of the other characters. Certainly by the end I was more concerned about Sonny's fate than that of the human protagonists.
Its been so long since I read the Asimov stories I can't say how accurately the film conveys their spirit. The 3 Laws of Robotics are used to move the plot along without going too deeply into their consequences, but there is enough to stimulate the imagination.
To sum it up, if you don't take the plot too seriously and ignore the crude product placement, its a fun film to watch with a few ideas to chew on after you have left the cinema.