Sorry you guys had trouble with Ember Data. Our first conception of Ember Data was that it would act as an ORM on top of JSON, and the architecture would allow developers to build adapters for many different kinds of backends.
Unfortunately, there is no JSON analog to SQL. Every existing backend forms their JSON differently, especially when you start modeling relationships. It would be like trying to build ActiveRecord if every team rolled their own query language for each new project.
We're trying to make this better in the long-term with projects like http://jsonapi.org, and https://github.com/rails-api/active_model_serializers for Rails. We'll get there someday.
In the meantime, we totally rebooted the Ember Data project to make it simple for people to customize how their apps consume JSON APIs. Most people we've talked to have been very happy about the fact that the defaults are simple to override now, and how much simpler the internals have become. We have a small amount of work left to do before we declare a 1.0 final; in the meantime, we've cut a 1.0 beta build that you can get from http://emberjs.com/builds.