I've been using Backbone exclusively for building Tutorialize's (https://tutorialize.me) chrome extension. One year ago backbone seemed like a very obvious choice, nowadays it's not the clear winner. I'm thinking about moving away from Backbone and trying out Angular or Ember. I've even thought about playing around with Dart. The most difficult thing for me has been dealing with all the things that Backbone doesn't handle out of the box. Things like zombie views, data binding, and namespacing just to name a few. The worst thing however has been the constant need to deal with strange quirks and bugs that I've found almost impossible to track down. I've posed a question to the #documentcloud irc channel three times and did not receive a single reply. I believe in the long run that the strength of a framework is about the conventions put in place. After all, isn't it about making development easier?