Ember is a framework that embraces convention over configuration. Even if you don't agree with every convention they have (I'm sure there are some things I wouldn't agree with) the convention means it will be easy for someone else to come in and understand what was going on.
I've read multiple places that every member of the Ember core team works on at least one production Ember site, keeping them in tune with how Ember is used, what developers need, what the pain points are, etc...
- Router
- Handlebars templates w/two way binding
- Components
- Data abstraction layer