"The moment I get confused, I check out of the movie. When all of a sudden stuff starts happening, and I don't know where I'm at... well, I think an audience has, like, an umbilical cord to the screen, and it gets severed when confusion comes in." --Quentin Tarantino

Well put. That's exactly what happened to me right in the middle of "U-571". Submarine movies are inevitably going to be claustrophobic, sweaty, noisy and dark -- tension turns this into masterful entertainment, confusion kills it.

The setting is World War Two. A squad in the U.S. Navy, led by Bill Paxton and Matthew McConaughey, have been ordered to seize a German U-boat that carries the radio codes used by Nazi submarines to plan attacks on Allied shipping. The movie opens with a cliché -- introducing us to all the boys at a big gala, before an urgent telegram comes in, informing them to return to their posts -- but there was still hope for the film at this point, because it has a promising appearance, with period texture perfectly captured. People looked, talked and walked differently in the 1940s; they had different ways of eating, washing, learning, wearing clothes. Many period films just plant obviously contemporary figures among archaic props, but the director of "U-571", Jonathan Mostow, gets the details just right.

There is tension on the boat before the big attack. It's a risky assignment, having to seize this sub, and these guys are sailors, not combat soldiers. If it goes wrong, not only is everyone dead, but the Germans will change their codes and tighten their security, and that may have implications for the outcome of the war.

At the decisive moment of action, when the Americans sneak onto the German boat by posing as a supply ship, I got completely lost as to what was going on. One of the sailors plants dynamite somewhere, and we can't tell if he's supposed to be doing so or not. Something explodes elsewhere, and the cause is never made clear. Someone thinks they've found a code book, and we're not sure if they have or not. A load of Americans end up in the water for no reason, and they don't swim the few metres back to their sub, they just scream and drown. Why?

This isn't one of those battle scenes that's supposed to disorientate us. It's an incompetently shot beginning to the film's middle section. So, with my umbilical cord severed, I found it hard to watch the rest of the film, with the guys in the submarine shouting impenetrable jargon and running around tight spaces, often with no clear purpose.

The scenes I did manage to follow were repetitive and silly: Every now and again a new obstacle would come up, and McConaughey would give an order as to how to combat it. Two of the other men would take separate turns to repeat these instructions verbatim, in hushed awe. It would be carried out to the letter, and work. Then they'd repeat it back to themselves, and say "Phew!"

Even some of the visual effects are shoddy. I'm amazed that Hollywood seems to be going backwards in this respect -- two or three years ago complimenting a movie's technological wizardry seemed redundant, but now, with releases such as "Battlefield Earth" on our screens, we seem to have returned to the days of shoddy "Star Wars" rip-offs. "U-571" has a torpedo attack that looks like it was shot by a kid throwing toys at a camcorder in the bathtub. And in the shots where people are supposed to be drowning, they look awfully in control: remember the scene with the rubber octopus in "Ed Wood"?

I feel sympathy for Mostow, who spent eight years of his life on this project, and has come out with something that can't be taken seriously. It did fill me with respect for World War Two veterans, but only in the sense that if their experiences were anything near as stifling or boring as the movie, then it's amazing they managed to carry on making important strategic decisions. The end credits reveal, by the way, that it was the British, not the Americans, who were actually the heroes of the German code-breaking operation. How nice that the filmmakers thought to tell us.