The book is fabulous, an amazing story masterfully written.
The movie was decent, but I wouldn't put it in my list of top WWII movies (which includes in no particular order A Bridge Too Far, Das Boot, 30 Seconds Over Tokyo, Midway, Saving Private Ryan, Patton, Theirs is the Glory, Battle of Britain, and 12 O'Clock High).
The flying scenes were outstanding -- some of the best out there. I was very impressed -- but that makes up only a small portion of the movie.