I'm designing a multiplayer turn-based game for Android (over 3g). I'm thinking the clients will send data to a central server over a socket or http, and receive data via GCM push messaging. I'd like to know if anyone has practical experience with GCM for pushing 'real-time' turn data to game clients. What kind of performance and limitations does it have?
I'm also considering using a RESTful approach with GAE or Amazon EC2. Any advice about these approaches is appreciated.