The Metro interface looks and feels like a smartphone or tablet OS, and following that theme is the inclusion of the Windows Store in Windows 8. This online shopfront is stuffed full of Windows apps - each designed to run on x86 Windows PCs, laptops and tablets, as well as ARM tablets and smartphones. Windows 8 apps follow the same design principle as Metro - being constructed of cascading live tiles of information, in primary colours. They all have social networking capabilities baked in as standard, and follow the same principles of interface, so that there is no real learning curve when starting to use a new app.
Native apps included with Windows 8 include the Mail email app, a calendar app and much improved contacts app called People. There's Photos, Music, IE, Weather, Finance, Sports and so on. Which is all very nice, but if you are an existing Windows 7 user wondering whether to upgrade, you almost certainly have legacy X86 software programs that you wish to continue to use. This is taken care of in all flavours of Windows 8 apart from Windows RT and Windows Phone 8.
To use older software in windows 8, you have to use Desktop. This is an app in its own right, and opens up into an environment that looks and acts in virtually the same way as Windows 7. Think of it as virtualised Windows 7, in Windows 8 (it's like a much more simple version of Classic Mode from when Mac OS X first came out). This is imperfect, of course, as it means that much of your computing experience in the 'new' OS is taking place in a window that looks suspiciously like your old one. Still, it's difficult to see how else such a great leap forward in Windows' interfact could be handled. And it does mean you can have the best of all worlds.
The Desktop mode in Windows 8 is different from Windows 7 in one subtle but critical way, however: there's no Start menu. In fact, wherever you are in Windows 8, either touching the middle right of your screen or mousing over there brings up the Charms menu, which comprises Search, Share, Start, Devices and Settings icons. The change takes a bit of getting used to, but is actually a lot more straightforward than the old way of doing things.
According to Microsoft Windows 8 is designed to be used by touch, keyboard and mouse - whatever is most appropriate to the task in hand. The corners of the screen are easy for mouse use, for instance, which is why the Start 'button' has disappeared, and in order to get to the Start menu you simply mouse to the bottom left. Similarly, for mouse users 'back' is top left, and to get to 'Charms' you have to go to the right and swipe. Keyboard navigation has been similarly adjusted. To get the 'Weather' app, for instance, you simply type 'weath...' and as you type the options will reduce until the Weather app appears. Meanwhile, page up, page down and so on, work as they do in Windows 7.
You can access search from anywhere, and the results are listed via the icons of the apps in which they appear. Simply click an app to choose results from that application. A search from anywhere combs the entire machine.
There are, of course, some down sides in these changes and to the fact that older software works only in the Desktop mode, but compatibility with other Windows 8 devices isn't one of them. For the price of getting used to some new interface tricks, you get to run all of your new apps across all kinds of Windows 8 devices, including PCs and laptops, but also ARM tablets and smartphones - in an interface that looks the same and has all your settings regardless of which device you are using.