I tend to think that Backbone is to Angular as Flask is to Django. The more ‘monolithic’ framework is really, really helpful, until you try to do something that goes against the grain of the framework. For this reason I tend to prefer micro frameworks like Backbone and Flask, though it usually does mean more code.
This is exactly why I continue to use Backbone, plus add-ons like stickit for model-view binding.
It remains small enough that most developers can read the source code and keep it all straight in their heads and it isn’t opinionated about how to accomplish something. The minimalism and flexibility is key for me.