What freaked me out about this site is that I have the OSX Mavericks wave as my background and the gradient transition on the site is the exact same color scheme[1].
I've written CSS for years and only recently started implementing some animations in my designs. I was worried at first when browsers started implementing it, fearing useless and insipid animations would sprawl around the web (like some jQuery ones). But like anything, if used sparingly, animations can improve an interface. Apart from adding life and being "cool" (probably the reason why designers implement them in the first place), animations add interactivity and affordance. Plus, they're less prone to bugs because the code is easier to read and write than jQuery alternatives, and the browsers' rendering engine usually prevents unwanted fluttering and infinite loops from happening.
Awesome stuff, the fluidness of those animations versus something made with jQuery is astonishing. I wonder what kind of compatibility would this have with older browsers?
The key to many of these effects is to animate both the transform and the position of the transform-origin simultaneously. Done correctly, it can give the animation a sinuous behavior that makes it much more interesting to look at.
[1] - http://i.imgur.com/QCyUUVd.jpg