(Added further details)
Not sure about the plan for phone-style devices, but native code applications will be available on tablet/laptop/desktop-style devices for both x86 and ARM.

The desktop itself works much as it always has. You'll only see Metro when first turning on the computer (there's probably a way to skip this), when opening the Start Screen (which replaces the Start Menu, retaining all functionality), and when accessing system settings (Control Panel, etc.). You'll also see Metro apps if you launch a file that is associated with one; PDFs, for instance, now open in a native Reader app.

Metro apps show up in Alt+Tab so you can use them seamlessly alongside desktop apps. If you've used existing fullscreen apps like Zune you'll have an idea of what this is like.

I installed it in VMWave Player yesterday. I don't know if there was a problem with the setup or VMWare, but when I entered e.g. Music Player, I didn't find any way to get back to the main screen from there. Ctrl-Alt-Del + shutdown saved me from that situation (or just closing VMWare Player of course). I was able to get to the non-Metro desktop on my second try, though.

It didn't seem interesting for now, so I uninstalled it.

Right after that, I decided to try Ubuntu 11.10 with Unity (in VMWare Player), I wanted to see why everyone is complaining so much about Unity.

Just as with Win8, I was quite lost with it, too different from Gnome. I installed "Flight of the Amazon Queen" and some platform jumping game on it, but then I couldn't easily figure out how/where to launch those installed applications.

These new, "easy" user interfaces are becoming too challenging for an old dog like me... Maybe a toddler knows right away how they work, I don't.

I note the requirements says 20GB and up. How much space do u need for the preview install (direct on HD or VHD/Virtual box etc) ?

A full-screen start menu interrupts what you're currently doing, a little menu at the bottom does not. Who thought it was a good idea to replace the start menu with a full-screen one? That's a really stupid idea, and I hope they will include a way to turn it off with the final release (but who am I kidding, they won't ever do that).

Ok, figures. Maybe I was expecting something visible which I can click with a mouse, tried some esc, backspace, whatever... too. I guess I was so enthralled by the simplistic UI that I was more in the Android mindset rather than Windows XP mindset, thus not trying out e.g. Alt-F4.

After using the Consumer Preview for the whole morning...

First thing first, lets start with the desktop. It features a much improved Windows Explorer. New versions of IE10 and WMP12 are also included. From what I saw, the interface feels a lot faster, and it is a lot more polished than Windows 7. The Ribbon is a nice addition for those with less technical knowledge, holding some commands that get used quite a lot. It is minimized by default, but when used, it allows you to do some things faster (revealing hidden files / folders now takes two clicks, instead of four (an example)).

IE10 on Desktop is amazingly fast. IE9 was very fast already, this is even better. It also feels like a lot more polish was put into it. I didn't saw much difference in the new build of Windows Media Player 12, the only thing I don't like about is that it doesn't open .MKV files, other than that, it is my primary media player. The performance of most other Desktop applications has been improved, they run faster than they did on 7.

The transition from Desktop to Metro requires a bit of figuring out. It is very easy to switch between the both, once you get a few hours of 'practice', try out different key combinations and mouse gestures.

Alt+F4 can be used to shut down a Metro app, but it is not necessary. Simply dragging the top edge of the app to the bottom will suspend it, in which it doesn't use much memory, and in a few minutes will close itself (afaik).

Windows key + Tab will list all Metro applications running, except the one you're currently using. Holding the Windows key after that can give you a fast way of navigating through Metro applications. I can't explain this correctly, but with Metro, now all applications are connected and share the data, making some things much easier do to.

Messaging application allows for Windows Live / Facebook chat. Bing's Weather and Finance apps are great.

Give it a few hours / day. You'll get the hang of it and do things much faster than with 7.
Drag the top of every Metro application down to the bottom and it will get suspended. The app will save its state, and continue from where it was suspended once you start it again.

Chuckle.

It's okay. I wouldn't have known it had touch screen features if I didn't read tech news sites. The UI looks pretty (if that's your thing) and I think a casual user will be able to click around to figure out how to do what they want. More experienced users will probably be annoyed until they learn more.

For my purposes, it's a fine gameloader OS! ;-)

As the screenshots start cropping up, I'm in two minds about this. I really like the Metro aesthetic and I'm quite open towards innovations in UI, but a lot of this seems terribly inefficient when it comes to the amount of information shown on screen. Because stuff like this sure is pretty, but makes you scroll down just because the designers decided they like their empty space. Somewhat reminds me of what I've seen of the vanilla PC interface of Skyrim.

Well, I wasn't planning to move on from W7 quite yet, anyway.

Does the consumer preview come with Movie Maker? Is it possible to schedule tasks the same way as you can in Windows 7 (Task Scheduler)?

Win8 is definetly geared towards tablet and touch screen devices. While it has the desktop, I felt that the combination and of Metro and desktop UI's were cumbersome at best. The usability just doesn't feel fluent enough on a desktop machine.

All in all, I'd like to try it on a touch screen just to see if the UI choices would feel more natural and fluent, but as a pure desktop OS's. I still prefer Win7.

Someone's jealous of Apple and decided to plagiarise OSes

I have yet to see any compelling reason to upgrade from Windows 7, which still works perfectly.