The title 'remarriage' registers the grouping of a set of comedies which differ from classical comedy in various respects, but most notably in this: In classical comedy the narrative shows a young pair overcoming obstacles to their love and at the end achieving marriage, whereas comedies of remarriage begin or climax with a pair less young, getting or threatening their divorce, so that the drive of the narrative is to get them back together, together again. The central idea is that the validity or bond of marriage is no longer assured or legitimizing by church or state or sexual compatibility or children but by something I call the willingness for remarriage, a way of continuing to affirm the happiness of one's initial leap, as if the chance of happiness exists only when it seconds itself. In classical comedy people made for one another find one another; in remarriage comedy people who have found one another find that they are made for each other.
(Cavell lists some contemporary examples here; one I'd certainly add as an exemplar is Peggy Sue Got Married.)
Anyway, so that's where we are, and, in so many ways, Mr. and Mrs. Smith could have been as good as Face/Off when it comes to Summer Action Movies With Great Overarching Metaphors -- spouses who are literally trying to kill each other; the physical destruction of the home mimicking the emotional destruction of the marriage, etc. Many of the dual meaning lines are quite witty, and Pitt and Jolie have good chemistry. Their Movie Star-ness carries them a long way, and some of the action sequences are kewl.
But. But while it's laid out perfectly on a structurally level, it just doesn't work emotionally. You understand that they're going to get back together somehow, but you don't really care about either of them. The movie wants to be The War of the Roses with a happier ending, but the resonance just isn't there. Compare it to Face/Off, in which you really are worried about Joan Allen and the marriage, as well as caring for the Gina Gershon character and the kid -- none of the depth is felt here.
Also big flaw: the movie's bad guys are never seen. We're left with the Smiths fighting an anonymous hitman/ninja army, and we never get to The Big Battle With El Jefe or find out how, exactly . . . [well, I can't spoil the whole thing.] You don't get the satisfaction that the genre would seem to require.
More: can we declare an official moratorium on Vince Vaughn still playing the role of Vince Vaughn? One comeback performance was enough, and he no longer adds anything to a movie. Nor is Adam Brody (the O.C.'s Seth Cohen) ready to take on a role of any significance in a movie, though some might be amused by the scene in which he's wearing a Fight Club t-shirt in front of Pitt. (I wasn't.)
Nor do we need to see another movie in which lots of stuff gets blow'd up and many people die but in which not a single police officer appears. (A final goof: for a movie set in the NYC area, you'd think they could have gotten rid of the "Los Angeles City Limits" sign in the middle of the three BMW chase scene.)
It's not as bad as Jeffrey Wells said it was. It's not a dumb movie; it's just not smart enough to work through its central conceit properly. You will occasionally laugh, and occasionally smile (any movie using an Air Supply song can't suck too badly), but you will leave disappointed.
There is one bonus, however: you'll probably see a really neat trailer first.