DJ Scotty,
U-571 has to be compared to something and Das Boot is a logical movie to compare it to because they both share the same WWII theme--allied forces fighting the Germans. Would you compare U-571 to, say, The Hunt For Red October? Probably not.
There is something else also. Although I love the loud, deep explosions in U-571, I find the special effects too artificial and I don't get the feeling of being there. Das Boot, on the other hand, captivates me and puts me in the middle of the action with its detailed portrait of life in a submarine at war. Now don't get me wrong. The special effects in U-571 are great and anyone who wants to experience deep, chest-pounding bass should consider buying the dvd.