I love that BB is such a small library. The concise docs at documentcloud plus the source code was all the reference as I needed, even for my first framework-oriented browser app.
I ought to connect with the community more, but so far getting up and running with it (and building a moderately complex app) has been a breeze, as far as Backbone is concerned.
I don't agree.
The fact is that BB is stable and has loads of documentation and live apps. Ember not so much.