Based loosely on the short story "Adjustment Team" by Philip K Dick. Which, I can tell you, is a pretty short story, about 8000 words. And of those words, The Adjustment Bureau doesn't really pay attention to many of them. The protagonist of Adjustment Team, for instance, is a mild mannered estate agent, who accidently ends up seeing behind the scenes of an "adjustment", where the supernatural Powers That Be are making small changes to the world in order to make large changes to the course of events. His response is to have a bit of a wibbling fit, and beg the Powers That Be to not kill him, he won't make any trouble. Because Dick didn't write about heroes, he writes about everymen.
Now, for Hollywood, this will not do. Matt Damon is a Big Damn Hero, and Hollywood likes making films about Big Damn Heroes. So the protagonist of the original must be Adjusted.
Instead, Matt Damon is a Congressman and Senatorial hopeful, who flubs his campaign on election night. The PTB didn't plan for this, so an adjustment is called for. The adjustment they make is that they contrive that he meet Emily Blunt, who is essentially his ideal woman, they have a fleeting moment which inspires him to make a concession speech that revives his fortunes, makes him a shoe-in for the next election, and so forth.
Unfortunately for The Adjustment Bureau, it seems that in some sense they're meant to be together, and luck, fate, whatever keeps throwing them together, while the Bureau need them to stay apart in order that their Plan for the world work out right. Then it comes to pass that Matt sees behind the scenes of the stuff they're doing, and so they basically level with him, hoping that he'll see sense and go along with The Plan. Unfortunately, The Plan means that he doesn't get to be with the girl of his dreams, so you can pretty much guess how that conversation goes.
So, this film is one part Phil Dick paranoia trip, one part chase movie, one part romantic comedy, in which essentially these sinister guys in trilbies try and interfere and prevent all the key moments of their burgeoning romance from happening.
And crazy as it may sound, it kind of works. The Adjustment Bureau aren't an evil bunch, their plan is to make the world a better place by ensuring that a nice guy with principles becomes a Senator. It's just that the nice guy doesn't want to cooperate. Matt Damon and Emily Blunt have a lot of chemistry, and the romance between them is surprisingly believable and non-sickening. Meanwhile the growing frustration of the Adjustment Bureau, populated by the likes of John Slattery and Terence Stamp is quite understandable; all they want to do is make sure the world is put to rights, and this idiot pair won't stop being lovey dovey and see the big picture.
So, rather than the usual PKD theme of someone wibbling in a corner doubting his own identity and sanity, it's all rather jolly, without really losing sight of the central themes inherent in the original story.
Sadly, and inevitably, the film can't sustain this long enough to reach a satisfactory conclusion, and delivers something as trite as the end of Minority Report which brought us to the climax and then said "and then they all went to live on a farm and live happily ever after" like we're five year olds, with parents who don't want to tell us what happened to the dog. It's not a horrible ending, mind, just a bit of a deux ex machina which leaves you wondering whether much of the preceding couple of hours were even necessary.
Ultimately though, it's a decent enough film which is worth seeing for all the good stuff in it, even if all the good stuff sort of runs out a few minutes before the end.