The movie overall was great. Especially liked the concept of the story unfolding with every question of the game. The portrayal of each character was really good and the way they showed Mumbai, I thoght was really good.
There were a few flaws - one in a reality show, the host is not really hostile to the participant when the camera is rolling and 2nd the song "Aaj ki Raat" from Don and the video shown on TV did not match. But these are minor aspects.
The characters that stood out for me, were the young actors. The kids who played the 2 generations of both Jamaal and his brother, were very good. I think they brought the movie to life.
Definitely a watch. Wouldnt say its a classic. But would deserve an Oscar. Especially if AR Rahman gets one.