Using graphene at work.
Absolutely love graphql as a technology. The pagination and ability to structure a query to pull a lot of data is nice.
As for some of the other comments - it's true you can't just write any query: but you can always add new fields, lists, connections (basically a pagination-friendly list), etc against arbitrary things on the backend. It's your backend, you control what data you serve.
The graphql-python stack is layered like an onion (graphene on top, graphql-core inside). You will probably be doing something like flask-graphql or graphene-django on top of that.
There is a huge negative for python <-> graphql for us, and it's the error system and promises. Perhaps this is what graphql servers in JS are like, but graphql-core hijacks python's error system by wrapping fields in promises.
So graphql-core is acting very very true to graphql's implementation in node: to the point it creating a mountain of breadcrumbs in sentry.
It also overrides the "next" built-in and tries to emulate express-style callbacks. Another thing ported from node into python that doesn't translate well imo.
Aside from that though: graphene has been really speedy, fast to work with. Documentation is getting nicer. The developers on the issue tracker are very nice. And as a general graphql thing: https://github.com/graphql/graphiql is really nice!
And one more graphql thing: It's typed. In a big API, being able to lay out stuff like that goes a long way. We're generating typescript types via schema.graphql output, and response types via relay. In a real big frontend project, it pays off a lot.
I recommend giving graphql a shot.