What are the differences between the theatrical version and the unrated version?
In order to achieve the more attractive PG-13-rating for the cinematical release, the film was cut and edited in terms of violence and sexual content as well as drug use. The unrated version was later released on DVD.
A detailed comparison between the theatrical version and the unrated version with pictures can be found here.
How much sex, violence, and profanity are in this movie?
For detailed information about the amounts and types of (a) sex and nudity, (b) violence and gore, (c) profanity, (d) alcohol, drugs, and smoking, and (e) frightening and intense scenes in this movie, consult the IMDb Parents Guide for this movie. The Parents Guide for Max Payne can be found here.
Is "bullet time" in the film?
Yes, although there isn't much of it.