Well... I got my YN560 yesterday. I like that it's shape is pretty much exactly the same as my 580EXII, that means they are share diffusers and stuff!
I also love the optical slave capability. I also LOVE the metal foot (which is honestly turned me off from most flashes) The only thing that weirded me out is the pilot button is red when it is ready and green when it is charging which is the opposite of my Canon flashes.