The entire movie seems like a great true story, only to figure out that it is a made up fable, of sorts, conglomerating a whole bunch of heroic stories into one made-up, over-the-top action film.  Regardless of that, it remains entertaining in the same vain as Hunt for the Red October.

QUALITY:
Good.  The picture is surprisingly clear and the sound is nearly lossless.

BONUS FEATURES:
Commentary.

The lack of bonus features is disappointing as I would have loved to see a featurette on the real U-boat heroes that inspired the story.  The picture and sound are great and the movie itself is very entertaining and will certainly keep your interest.