We've been working with AngularJS for a few months now - as we slowly transitioning our Flex app to HTML/JS app.
I have to admit - AngularJS is not the easiest framework to learn. I had a hard time understanding some of the terms that Angular uses. One example of this is the Angular controller - in my mind it does not resemble the traditional MVC's controller, I wonder if it can be called something else.
But once I got through the initial hurdles. I started to liking it more and more. The two data binding is a highlight for me - especially coming from Flex. The ability to extend HTML is really nice too.
And lastly the people behind AngularJS are super. I ranted a couple of times on Twitter and Igor has been helpful. The Angular Google Group looks to be a great place to hang out - but I have to warn you is very noisy.
If you are interested in learning more about AngularJS - I found Lukas's blog One Hungry Mind to be a great resource - Lukas writes (and screencasts) in a way that just works for my brain.
If you are coming from Rails background and want to know how AngularJS might integrate with your Rails app - take a look at Centresource example, better still watch the two videos:
Hint: if you are willing to unleash the AngularJS power - you can let it takes over your Rails view and let your Rails app just be an API app - mind blowing stuff I'd say.