I'm starting to think that there is just something about Melissa McCarthy that means she ends up in films that have an awful setup but a genuinely funny second half. Much like Ghostbusters: Answer the Call, once Spy gets the character introductions out of the way and just runs with the premise it becomes a very enjoyable and outright funny movie. In order to get to that part, though, you do need to wade through a swamp of awkward moments and gags that feel like someone found a high school student's improv diary and just started copy-pasting. I mean, why is the CIA office infested with bats? Even if you buy into the (crap) running joke about how the office staff aren't treated well, the logical escalation of the gag is to start with a suspected infestation, show rats and then end with bats, but instead we go from 0-100 in one scene then just hover around 20 for the rest of the film.
Awkward moments of humour aside, the action, script and plot are all tight enough to keep you entertained. There are no terrible performances, though Peter Serafinowicz should get an award for saving a terribly scripted roll. The outcome remains mildly irritating, but when you look at his character abstractly it had all the Jar-Jar Binks like qualities required to sink a film entirely, so frankly I feel he did an astonishing job. In fact I think it's fair to say that, for the most part, the incredible cast help lift a lot of mediocre side characters out of poor-writing hell. Both Allison Janney and Jude Law probably also deserve serious credit for making their characters far more appealing and nuanced then their scripts should have allowed. On the other hand, you have Jason Statham going the other route and hamming up his performance so much it becomes brilliantly funny; I can't help but feel he had an enormous amount of fun in this role.
Which I think is the main takeaway that shines through. It feels like everyone involved in Spy just had a lot of fun, which helps lift the whole film. It feels exactly like what Mortdecai should have been, but actually pulls it off. It's not a film I'll be rushing back to watch and, honestly, you won't miss anything by skipping it, but if you fancy an easy laugh or two then give it a look.