I think the point is that CSS3 is hardware-accelerated on platforms like the iPad / iPhone, whereas the canvas isn't - it runs like a bit of a dog on those two.

I think the point is that CSS3 is hardware-accelerated on platforms like the iPad / iPhone, whereas the canvas isn't - it runs like a bit of a dog on those two. I personally would prefer using the canvas though, especially if it becomes HW accelerated across the board.