Not really a spoiler, but I will put a spoiler warning on here just in case. First half of the movie is excellent, suspenseful and ultra realistic. The second half however goes a bit too far and loses its realism and the suspense takes a hit as a result. The film is most suspenseful when things are in the realm of possibility, but after one too many death defying feats one after the next you begin to realize you are just watching a movie and the suspension of disbelief is destroyed for the more avid/sophisticated viewer. I know, I know, I sound like a total film snob, but I think directors try to do too much to create suspense and they end up having the adverse effect by going a bit overboard.