Microsoft is switching to a UI that is ALREADY tested... as you yourself point out it's a very similar UI to those used on mobile devices, and primarily BECAUSE it's already used on mobile devices.

is this good or bad? I have't tried the consumer preview yet but I did check out the puff-piece for it... and honestly I don't like the huge icon UI... on both Windows and linux Mint, I like a mostly empty desktop, and put all of my most common launchers on a toolbar and everything else in the Menu... Reason being that the running application should fill the desktop, while at the same time I should have easy access to switch to or launch other apps.

on Linux Mint, I love the multiple desktop switching and the split-pane windows. I also love the ability to MAKE custom toolbars. I've been using Word Perfect since before Corel acquired it (early 90's), but when they did and they changed the entire UI I LOVED it... I can make any of the toolbars in the UI suit my needs, and THAT's how an OS's UI should be as well. Corel's UI hasn't changed much since then except to expand the possibilities of what can be customized.

Then again, I also don't like touch-screens, which is what the Windows 8 UI is based around...