This movie is the sort of thing Hollywood would have turned out in 1943 if they'd had the technology to do the special effects. In other words, it's a typical wartime propaganda film, where the American sailors are wonderful people, and the Germans are horrible, evil, murdering Nazis. (In reality, the one clearly heroic action in the movie is the self-sacrificing effort of the German captain to home a destroyer onto his boat after it has been captured, though the way it's portrayed you get the impression the director wanted it to seem like just another bit of evil treachery.)
Okay, it was very popular. There's lots of action, and a great deal of money and effort was expended in making sure that the u-boat itself was completely authentic. The producers actually went to the expense of having a full-scale Type VII u-boat constructed, to the original plans, though the replica boat couldn't dive.
Unfortunately, that was the end of their efforts at authenticity. It's true that all submarines operate on the same basic principles, but it is certainly not true that the controls are the same from country to country. I suppose director Jonathan Mostow decided that it wouldn't make much of a movie if everyone died 20 minutes into the picture, so somehow the Americans, after capturing U-571, manage to dive it without killing themselves, and then fight a submerged battle with another U-boat, using one of the nuclear torpedoes the boat seems to be equipped with. (Hollywood loves to blow stuff up, and the more spectacular the explosion the better!)
If you like action movies, don't care about real character development, and know absolutely nothing about U-boats, submarines, or history, you might just enjoy this. Lots of noise, explosions, and every war movie cliché ever thought of are right here for your enjoyment!
A couple of good U-boat movies, just to compensate for this disaster: