The story was good and the acting was mostly ok (Kretschmann, in particular, was good) but the movie was missing something. Tension, a sense of desperation, something to make me care. It's an ok movie but not even close to great.

I liked the back and forth between scenes aboard the American and German subs trying to show the differences and similarities. What I didn't like was the stereotypical "promise to come home" opening, the lame Captain's speech, and the odd jump in the timeline. The ending was ok, the movie was alright, but I certainly wouldn't go out of my way to see it.