1. Internet Explorer 10
I know, I know. We're just as shocked as you are. But IE 10 is fast, fluid and tons of fun in Metro. Swiping to navigate back and forward makes perfect sense; it's how every mobile web browser should navigate. Double tapping zooms in, or out, even when IE is running in Snap state (a small, minimised version that runs in the side of the main window). Zooming and panning is fluid, reacting just as you would expect a natural object to react. Momentum speeds up and slows down in relation to your touch. And if you do need the power of a full-throated, plug-in capable version of IE, you're just two clicks away from the Desktop version.
2. Semantic Zoom
Semantic Zoom makes organising all your apps a snap. Pinch the screen to zoom out and all of your Start screen tiles minimise where they can be easily re-arranged. You can drag individual tiles, or groups of them, to re-order how they appear in Start without having to scroll endlessly.
3. App Bar
Metro banishes application chrome, but recognises that you need it sometimes. So Windows 8 makes it accessible via an App bar that launches when you swipe up from the bottom edge of a screen. It's a best-of-both-worlds way to have controls when you need them, and screen real estate when you don't.
Show in-app commands in a couple of apps by swiping up from the bottom edge of the screen.
4. App Management and Switching
In the developer preview you could swap between running apps in Metro by swiping from the left edge, but the consumer preview takes that functionality to the next level. You can do a left side mini-swipe, or use the mouse to go to the top left corner of the screen and pull down, to see all the running apps. You can drag an application tile from the Snap state to the bottom edge to kill it. And of course you can still have apps run in that Snap window in a minimal state.
Charms have also been refined in the consumer preview. Swiping from the right side brings up the Charms, which allow you to search, access settings, share data with other apps and more. The "show desktop" element is gone. The spacing has been widened slightly, both to make them more accesible for lefties as well as righties, but also to let you accomplish tasks quickly and get back to work. So, for example, after you hit the Settings Charm, the settings themselves appear where your thumb already is.