Having NOT seen this in a theater, as it was only released on DVD in the U.S., I can only comment on the DVD version. I have seen half of it in English (in which Germans are speaking excellent English), and all of it dubbed in German (released in Germany, with no subtitles). There, of course, the Americans are speaking German all too well.
This film must be taken for what it is, I think. A showcase for W.H. Macy (his acting is not superficial, nor are his interactions with his wife, whom he had to leave as Chief on the U.S.S. Swordfish). Sure, the numbers and names of ships are all wrong. Did NO Kapitän-Leutnant serve underwater with his blue tunic on, as suggested by one reviewer? This is a good introduction to Til Schweiger, who really is of matinee-idol stature and appearance, as Captain of one U-Boat, and the first watch officer (Thomas Kretschmann) really shows his acting talents....compeletely different in Stalingrad, The Pianist, U-571. Perhaps Mr. Macy was not challenged by the role, and the meningitis outbreak is unbelieveable....but aren't movies unbelieveable. Do they not require suspension of disbelief, even the best?
I did not expect the Barry Lyndon of U-Boat movies. The sets are too wide, the U.S. sub is too brightly lit...but the "best set" film has been done (Das Boot) and took a year to film (see the Director's Cut DVD). Other criticisms are hollow...the flag, the seaman appearing to wear a modern German Navy tunic (I have seen them, I do not think so, but it is a brief shot. At least no one is wearing Chuck Taylor sneakers! And the back and forth between Macy and Kretschmann (Captaincy shifting back and forth depending on the conditions and likelihood of being captured by Americans or Germans--all within a few hundrend miles of the U.S. coast (which is realistic)...ending with Kretschmann ending up as a P.O.W. with the guarantee of living past the war, which was the intention of the Captain played by Til Schweiger.
All in all, it may not be historically accurate, but is a drama set in wartime, with some atypical themes (German taking prisoners against orders), some suspense...you want more from a film that did not get theatre release? I recommend it, but of course it is not a chick flick (probably an un-PC statement although commonly used), but it might become one because of Til Schweiger! So see it!