In terms of performances, most everybody turned in a great performances, especially the main cast...Saif, Vidya, Sanjay, and Sabyasachi Mukherji (the father). I wouldn't rave about Saif's performance as other reviewers have done. He was good...but not as comfortable and edgy as he was playing the villain in Ek Hasina Thi (I think his best performance yet). Vidya Balan was good for a newcomer...but I'm not sure her looks are suited to the typical Bollywood movies being made otherwise.
The music and art direction, i think, are the main heroes of this film... give the film that extra edge..and is what you carry with you out of the theatre.