In my opinion it's one of the best ship movies, and one of the best war movies, ever made. Highly recommended.
As I understand it, it was originally a West German TV miniseries. I saw a two-hour version of it in a theater (in Norfolk, Virginia) when it was new. It was promoted as an anti-war movie, but it puts its message across by being realistic. (The actors were told to stay indoors throughout the shooting, so they'd have realistically pale complexions.) Some of those model shots are pretty hokey, but lots of folks, including me, overlook them in the context of a great movie. The interior shots of the U-boat are stunning.
Several versions of it were released on DVD. I like the "director's cut," which has quite a bit of additional footage and some extra features - including one on the making of the movie. I haven't seen the Blue-Ray version, but I may seek it out. We just bought a Blue-Ray player.
Quite a long time ago I read an article about the movie in the Naval Institute Proceedings. The author of the article was a former naval officer who'd served as a consultant for the movie. He said that he and the producer had agreed on one deliberate concession. The men in the crew sort of wear their emotions on their sleeves. In reality, that officer said, they would have worked hard to conceal whatever fear, tension, and desperation they might have been feeling. I don't think of that as a criticism of the movie, though.
Another point that I personally can't attest to: a German professor at the joint where I work said that the original German-language version is like an encyclopedia of German dialects and accents. The DVDs give you a choice of the original German or a dubbed English one - and the dubbing isn't bad. (Jurgen Prochnow, who plays the captain, speaks very good English and did his own dubbing. I imagine some of the other actors did the same. The version I saw in the theater was in German, with English subtitles.)
Anybody with any interest in the naval side of WWII really needs to see that movie.
Youth, talent, hard work, and enthusiasm are no match for old age and treachery.