Just cooked up an EmberJS project and wanted to share some thoughts on the framework as a whole and also throw some gotchas.
1. Many things work out of the box. However, when you need to do something that is not out of the box, you will find few resources to help. Worse yet, things change so much that found resources may not.
2. Some things are shockingly easy to do. Some of those things include data validations, 2 way binding and active record (rails) integration with active model serializer.
If I had one recommendation, it is to not use templating languages or extensions like emblem. I used this during my first project. It is similar to slim or haml and makes it super easy to see how the markup will be. But the downside is that whenever you need to do something unique, you will fight with it in order to get it implemented.