Film Pretty damn good, but not flawless.
For a spy comedy, this movie has it all. Witty banter from a talented cast, black and blue humor of all sorts, oddly nuanced characterization, and a compelling plot. All these qualities do tend to make the film feel overcrowded and a tad rushed, but these drawbacks aren't especially noticeable.
What is noticeable is that the comedy, hilarious as it can be, revolves too much around obnoxious, unlikeable characters while slighting those who are funnier or more endearing. Rayna wears out her welcome fast, and isn't given a ridiculous death scene to make up for it (or any death scene at all for that matter), whereas Aldo's gimmick is explained to the viewer without his character ever developing into anything beyond it. Consequently, the film neglects funnier characters like the icily hammy Rick Ford and the snarky-but-still-vulnerable DeLuca, as well as sweeter ones like the Adorkable Nancy.
That being said, I recommend it if you're hankering for a fine action-comedy, albeit one that doesn't entirely live up to its potential.
Film Funny and amazing
Go see it. The movie is 2 hours of laugh-out-loud fun. It's hilarious, well written, and amazingly acted. Melissa Mc Carthy is brilliant, and Jude Law, Jason Statham show amazing comedic talent. It has amazing action scenes on top of all this. You owe it to yourself to go see this.
Film If Pam From Archer Had Her Own Show
If you watch the TV spy comedy Archer (and you really should), you'll know of a supporting character in it called Pam. In the first season, she's an uptight, frumpy HR lady who is the constant victim of bullying and fat jokes. By the third season, she's a bare knuckle boxing, drag car racing, unparalleled sex fiend. Spy is essentially that transition, squashed down into a two hour run time. And that's a good idea for a movie.
That's not to say it is unoriginal. Spy might look like a Johnny English derivative from the trailers, but it goes in a completely different direction. Rather than it being about an idiot spy who can't get anything right, the protagonist, Susan Cooper, is an extremely capable field agent who has simply been denied any opportunity to excel in her job, because her colleagues see her as just some fat dork. The fact that Cooper is a fat dork and a badass is what makes the show work.
Much of the humour is her clashing against the toxic masculinity of her colleagues; a James Bond expy, a Jason Bourne expy, and the world's most brattiest arms dealer. It could easily have been a parade of mean spirited fat jokes, but actually those are few and far between, and most of the contempt aimed at Cooper is at her alleged incompetence, lack of grace, and frumpy outfits (which she is forced to wear by her superiors). Instead of despising such bullies, we never take their exaggerated macho posturing and pathetic elitism too seriously. They are still likeable, in spite of their snobbery.
It isn't a flawless film by any means, but it is never dull. Considering how horrifically violent and foul mouthed it can get, it still manages to feel all in good humour and taste.