It is a good movie, especially if you are an analytical thinker; it's kind slow moving at times though because of all of the research that is presented.
The only real problem I had with the it was, that in my opinion, a person could get the impression that "mental assent" (just believing some facts about Jesus) makes a person a Christian. There was really no emphasis on repentance or being Born Again, even though his life was obviously changed after he met Christ...it just wasn't talked about why. I never read the book, but from what I understand, these elements were talked about there and maybe just removed because of time restraints in the movie.
It is worth watching, but if you are going to be seeing it with a non-believer, just be ready to fill in some holes that the movie left.