Very flexible — clients decide which fields of which entities they need.
Documentation and test UI are available by default.
Code looks ugly.
N+1 selects problem is hard to solve (most probably — with some ad-hoc).
It’s harder to test as you don’t know all the use cases.
Not a binary protocol — is not that efficient in terms of network utilization.
Mutations are even harder to implement, so it’s not the best idea to even try it.
Here is the video in Russian: