The story, taken from the book of the same name by Ian McEwan (I haven't read it, but heard it's great), is a novel and intriguing story, both in its plot and in the creative way that it is unfolded. I'm not sure how it went in the book, but Christopher Hampton's screen adaptation does some wonderfully clever plays on subjectivity and viewpoint, showing us a scene through one character's eyes, and then revisiting, Rashomon style, the same scene through another character's eyes. Sometimes it is signaled by a visual link, such as a dropped earring, while other times it is intentionally unmarked, so that you only realize partway through that the timeline has folded on itself. The scenery is as lush as you would expect for an epic of this scale, with the first part of the movie shot on a sumptuous Victorian manor estate (actually, an old pile semi-restored from harder times that this film is probably helping to save), and the latter part with vivid depictions of Normandie, London, and Dover during World War II. Many of the images are the sort of beauty that stay in mind long after the film: close-ups on Saiorse Ronan's face and eyes, soldiers walking through a French apple orchard and later finding the beach, both Keira Knightley and James McAvoy diving into the water at various times. The music by Dario Marianelli is pitch-perfect for the tone of the film, and brilliantly incorporates the sound of an old Corona typewriter throughout (as well as piano performances by the masterful impressionist interpreter Jean-Yves Thibaudet). And there's a very effective use of utter silence as "score" in Vanessa Redgrave's scene as the older Briony, where the absence of music and sound creates an intense vacuum, signifying the emotional weight of Briony's guilt. (The technique is unusual, but can be used to great effect -- Bob Fosse's All That Jazz comes to mind.)
One thing I didn't expect, and that ever-so-slightly disappointed me, was that I found the film a bit cold and detached. Everyone was talking about having tissue handy, and I cry at the slightest provocation, yet this film did not make me cry. (Okay, my eyes moistened a few times, but the tears never flowed.) In retrospect, I think the fault was mine rather than the film's, in that I was just expecting it to be something other than it was. The romance between Cecilia (Knightley) and Robbie (McAvoy) was never really explained, but then that wasn't really the point. It wasn't about them, so much as it was about Briony. The title of the film is not "Love In Wartime", it's "Atonement", and that should have been a big clue to me. That's not to say that there aren't some very poignant scenes of the lovers, separated by events including the war. But the director made a choice not to cue up the violins and make any gushy scenes, instead keeping a taut psychological tone throughout, building the pressure for the ultimate need for atonement. Appreciated for what it was meant to be, rather than what I expected, it was a brilliant film.