Been using the Release Preview for a few days now, and have to say I really like it! I'm using it on a desktop and at first I didn't like Metro, but after a bit it's started to grow on me. There's a great Twitter app on the store and the People hub is good for Facebook. I also like how responsive and fast it is as well as the new features like native ISO mounting, the new Task Manager and what they've done to Copy & Paste. I'm planning to move over to it when they release the RTM version, I suppose it's down to preference, but I can't think of a reason not to upgrade, sure Metro might not be for everyone but it is easy to switch to the desktop and there are bound to be hacks in the next few months to make Windows 8 automatically boot to the desktop