I went down the path of learning Relay instead of Apollo. I'm regretting this decision. Relay is too restrictive, and the relay compiler is far too sensitive for most server side endpoints.
I'm curious about the second part of your statement, the compiler being too sensitive for your server side endpoints, can you elaborate on that a bit?
The second big issue was that relay modern decoupled the networking logic, so having a series of chained queries is something you either have to handle yourself or write your own networking logic for. And because creating dynamic queries can't be done with relay it's a bit annoying that this logic isn't handled automatically for you.
My biggest gripe happens to be the lack of flexibility around dynamic queries. You can't define the data you want back at run time, which feels defeats a major point of GraphQL.
Apollo supports dynamic queries with higher-order components. It might be a case of the grass looks greener on the other side, but I felt as soon as you try to do something bigger than a todo app with Relay you start to feel the restrictions.