While you can indeed perform larger, more complex requests, GraphQL by nature forces queries to explicitly ask for everything you want to get back. As a result, we're not wasting any capacity giving you back a bunch of data for an entire object that you don't need like we would in a normal REST API request.
The thing that I'm most excited about with all this is the fact that we're building new GitHub features internally on GraphQL as well. This means that unlike a traditional REST API, there will no longer be any lag time between features in GitHub and the GitHub API.
API is a first-class product now. API consumers get features as soon as everyone else!
Please make sure to give us feedback during this alpha stage! https://platform.github.community/