I'm not a fan of Ember, but it's focus on tooling, developer experience, and sticking to it's core principles in the name of consistency is something to be admired. It's not as shiny as Cycle or React, but if you started working with Ember years ago, you've had reasonably robust tooling all along (as opposed to the bleeding edge constantly breaking crap of the other frameworks), and have been able to reuse your knowledge for years, so you're potentially quite productive.
Why is that ? I've never used Ember, but it seems like the framework with the best tooling and backwards compatibility track record. Maybe I'm wrong, I don't know.
The templating is very inflexible and the routing becomes extremely complex as your application grows in size. There are also a lot of gotchas with the runloop that require time and experience to understand.
