If nothing else, 'All the Birds in the Sky' deserves a ton of credit for the way that it more or less vaults over the high-concept obviousness of its premise like Evel Knievel jumping eighteen double-decker buses. (I should probably stop there, because I don't think I'm going to write a better sentence than that, but I'm going to press on.)
What I mean by that is that as soon as you hear that it's a story about a girl who grows up to be a magician and a boy who grows up to be a genius scientist and that they have to team up to save the world, there's a certain degree of ossification of concept that happens immediately. You just know that the magicians don't cotton to rigid hide-bound scientists, and the scientists hate the irrationality of magic, and they don't get along and it's up to these two best friends to find some way to make the two work together, because thesis-antithesis-synthesis is pretty much ingrained into SFF authors as an easy way to get a three-act structure out of their idea.
But Charlie Jane Anders avoids the obvious plot structure, more or less, by taking the audacious approach of ignoring it completely for a good three-quarters of the book. Instead, she focuses primarily on protagonists Laurence and Patricia initially as damaged kids from messed-up families whose friendship is just about the only thing that keeps them alive through their childhood, and later as slightly damaged adults who are recovering from a lifetime of trauma and who wind up becoming friends all over again. And oh yes magic is real and so is weird impossible super-science. It's actually a brilliant approach to the material, and the majority of the book flies by in an immensely readable fashion.
The end does suffer a bit from having to come back to the premise--there's a bit of Idiot Ball plotting as Laurence and Patricia suddenly find themselves on opposite sides and spend a bit of time assuming the worst about each other in an unconvincing manner--and I'll admit to not entirely liking the way that all the romantic sub-plots developed, but I confess that could be due to unfair expectations on my part. I'm a big fan of Charlie Jane Anders, and she's awesomely sex-positive and non-heteronormative, and I kind of thought that would come out more in the book than it did. But I've always felt that one of the cardinal sins of a reviewer is saying, "The author didn't write it the way I would have," so I will freely give her a pass on the latter issue.
Overall, the book is charming, witty, human and moving in a very fresh and modern way. It feels like a novel about people who live in a fantastic universe, rather than a fantasy novel, and I hope Charlie Jane Anders takes that as the compliment it's intended to be. I greatly look forward to her next work.