NOTE: This article has been completely revised for the new Windows 8 Release Preview.
The Windows 8 Release Preview (here's the Windows 8 download) has now been released.
Although the Windows 8 Release Preview is far from finished (with more changes to the desktop user interface still to come before RTM at the end of July), this is an operating system that has matured significantly since the Consumer Preview release in February.
Metro is here to stay, but there are numerous improvements to the way you switch apps and open Charms with the mouse and trackpad; significant improvements to the Mail, Calendar, People and Photos apps; the addition of Flash to Metro-style IE; more Metro apps to try out; more attractive live tiles and a better range of colours for personalising the Start screen.
You may not find Metro as disturbing as you think, especially when more notebooks support the full set of trackpad gestures.
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There are improvements on the desktop as well, including minor interface changes in Explorer and improved multi-monitor support plus privacy and navigation improvements in Internet Explorer.
Performance and responsiveness are improved from the already speedy Consumer Preview; rough edges are getting their final polish and the big picture of Windows 8 is coming together. So what does that big picture look like?

Running the Windows 8 Release Preview

First of all, it's worth noting that the Release Preview is only for x86/64 PCs; there isn't an ARM version that you can download and try out, since there aren't any ARM devices that will run it.
That's because of the extremely custom way that ARM devices are built, where not even the way to control a physical button is standard. Microsoft isn't supporting tablets built to run Android or WebOS, either.
Much of what we're seeing in the Review Preview will be the same on Windows RT systems - Windows RT is the name for the ARM version of Windows 8. Most features - from the Metro user interface to the touch gestures, to the Windows desktop and built-in Windows tools such as Explorer and Task Manager - will be practically the same.


Windows 8 Release Preview: Start apps
Microsoft has even confirmed it will offer Flash functionality for IE on Windows RT (at least on what it calls the "initial delivery of Windows RT PCs"). But until we see it in action, we don't know what Windows RT performance and battery life will be like.


Windows 8 Release Preview YouTube
Release Preview doesn't include the desktop Office apps that will be bundled with Windows RT either - and of course it runs all the x86 desktop apps that won't work on RT.
When you download the Release Preview, installing it is as simple as for Consumer Preview. You can start the installation directly from the web page, instead of having to download an ISO file and burn that to an optical disc. You can still burn an ISO if you want, and the installer can also create a bootable USB stick so you can download Release Preview once and install it on multiple machines.
As with Consumer Preview, how much of a previous Windows system you can keep when you install Release Preview depends on which version you're upgrading from; upgrade from Windows 7 and you can keep programs, Windows settings, user accounts and files; upgrade from XP and you only get accounts and files.
Unlike Consumer Preview, you can't upgrade from any of the previous Windows 8 preview releases; what you get is a clean installation with all your files moved into a WINDOWS.OLD folder where you can retrieve them.
If you can copy the files to an external drive it's much faster to do a clean install (which took ten minutes to get to the personalisation screen on our test PCs) than an upgrade from Consumer Preview (which took 30 minutes on all our test PCs).