Without a doubt, cinematically this is a visual tour de force. The one-shot approach becomes a distraction, at times, especially when one ponders "how did they do that?", but generally not enough to take away the wow factor.
The story, and dialogue, not to mention logic are the real problems that take this movie from great, to merely good.
The initial concept of sending two men on an imperitive mission to save 1600 men is ludicrous in itself, especially in a war where men were gassed and gunned down by the thousands. Sending only two of them into unknown situations, in no-man's-land was illogical.
Then there was the fact the hero seems to never get shot by enemy soldiers, despite being in dead-duck situations. When he does get injured, his wounds seem to magically heal and disappear instantly. Director Sam Mendes must have never had the concussive effects of explosions explained to him, because while some fall from explosions, the heroes seem immune to physics.
The most ludicrous scene involves booby-trapped explosives, and a collapsed ton of rocks leaving not only no visible injuries, but no effects at all on clothing or hearing. But there was dust in the eyes.
There are many more scenes involving lack of logic, or credibility.
Over-all, the movie is worth it for the cinematography, attention to detail, costumes and acting, but the trite story, and credibilty problems drag it down from what it should, and could have been.