I mucked around with it once. I haven't found a project to really use it on yet, as most of my projects are more document oriented. However, in general, I feel as though a lot of javascript mv* are applied to too many situations. They really make sense in a web application, not a site that is primarily document based like wikipedia, reddit, etc...though the lines between "application" and "document" really get blurry for a lot of things. While it is a nice idea to have the server side really just act as an API, I've yet to see a client side templating system that is as friendly as something like jinja2. I think a lot of the javascript solutions mix a lot of the presentation and logic/behavior, which I'm not a fan of. Anyway, things like backbone.js and angular.js definitely have their place, but they seem to be a little bit of a thing right now, and perhaps extended to things they don't lend themselves that well to.