The movie is good
I've heard that the book is excellent but have not had time to read it. The movie is considered faithful to the book. The History Channel did one of their "History Verses Hollywood" episodes on the movie featuring a panel with many survivors of the battle. They rated it about 75% history and 25% Hollywood, which is about as good as any movie gets. About the only recent movie I can recall that was considered more historically accurate was "Blackhawk Down".
As an aside, the movie I remember being the most faithful to a book was "The Execution of Private Slovak."