I loved the movie even more than you. Jon Chu is brilliant at letting the camera tell the story. He also really captures the life and heart of the Washington Heights community in a way that is rarely done in a mainstream film. I think the film actually improves on the stage musical, which has great characters and music but tells a story that is rather slight.
Personally, I thought the casting choices were fine. However, would it have made sense to cast either Sonny and his dad or possibly Vanessa with black Latin-American actors?
I had no problem with the film's length. I'm definitely going back to see it again in a movie theater, perhaps as soon as tomorrow.