The benefits of CSS animations are plenty. Unfortunately, support is still very scarce: the Webkit team brought the animation property to the CSS3 specification. Mozilla have only very recently added support in Firefox.
however, both Microsoft and Opera have announced support in their upcoming releases.
In my opinion, CSS animation are much easier to write than Javascript animations, and don't require external libraries such as jQuery.
For many things it's not hard to get 60 frames per second with javascript and you have tremendous flexibility that is hard to replicate css, in my experience. For instance, I had a hard time synchronizing all my css animations but found it easy enough in javascript.
I know there are a ton of advantages to using css for animation, so why do most people use javascript? Easier to code?
Oh and btw, this is awesome. I will definitely be using some of these animations in the future. Thanks :)