I'm not a fan. A centered dock does look pretty, but to me it's not as intuitive as a left-aligned screen. Especially since you would be navigating to the "Start" menu a lot. Getting my mouse bottom left is more natural than "some random offset of dead bottom center".

I can't tell if the icons get larger as you hover. That sort of magnifies this problem, as the start button would shift left as other icons are highlighted.