This review is a bit more spoiler-y than usual, but it's not as if there's really all that much to spoil in what is a fairly standard Hollywood action flick.
The setup, which you're no doubt familiar with from the trailers and ads, is a clever one. CIA agent Evelyn Salt (Angelina Jolie) is interviewing a Russian defector who claims that a Russian spy, who has been living in the US under deep cover for years, will kill the Russian president tomorrow at the funeral of the American vice-president in New York City. The name of that spy: Evelyn Salt. Salt protests that this is nonsense, but she runs as soon as she gets the chance.
This being a Hollywood movie, and Angelina Jolie being the star, we know that Salt will eventually be revealed to be a good guy after all. But one of the movie's biggest surprises, and one of the things I most liked about it, is how long it sustains the ambiguity about whether Salt is or is not a Russian spy, and whose side she's really on. Even the movie's climax is less heroically redemptive than usual, leaving Salt as more of an anti-hero than a hero (and even more blatantly than usual setting up a sequel).
What works in the movie? Jolie, above all else. Even during the first half of the movie, when Salt is doing horrible things and we're being led to believe that she actually is working for the Russians, she is still somehow a character; we're rooting for her to get away with things we shouldn't want her to get away with. Credit for that goes almost entirely to Jolie, who does such a good job of establishing Salt in the opening scenes as someone we like and want to trust that we are willing to stick with her even as the movie calls upon her to perform far more heinous acts than we're accustomed to from even our most morally ambiguous action heroes.
The action scenes are also terrific. An early freeway chase in which Salt leaps from the roof of one moving vehicle to another (several times) is a thrill, and the scene at the vice president's funeral is cleverly staged and imagined.
There are a few moments that strain credibility. I'm pretty sure that you can't actually use a cop and a taser to drive a car in quite the way that Salt does during one chase (though it does make an amusing scene), and the movie's makeup is sometimes less than compelling (Jolie as a blonde? Almost always a bad idea), becoming laughable in a short scene where we're expected to believe that Salt is convincingly passing as a man.
And there's one glaring plot hole near the end (and this really is a bit of a spoiler if you haven't seen the movie, so you might want to skip the rest of this paragraph): After the battle between Salt and Winter (and was I the only one who couldn't stop thinking "you can't fight in here; this is the War Room" through that whole scene?), when Salt is arrested and the Secret Service escort the President away, why doesn't the President tell anyone that it was Winter who shot everyone and knocked him out? There was an easy fix available; I don't know that I'd have found it convincing, but I'd have gone along with a simple line of dialogue like "the President has regained consciousness, but has no memory of what happened in there." But then we wouldn't have gotten the nifty strangulation of Winter, I guess.
If you're not into the Hollywood "that blowed up real good" genre, this may not be for you. But as such things go, I thought the unusually prolonged attempt to sustain some ambiguity about the protagonist's morality and the unbridled star power of Jolie made it a fine piece of summer popcorn entertainment.