I'll get this in before the hundreds of "omg don't want" posts. Windows 8 is significantly different from previous versions, not just for the interface which takes some initial getting used to (although many, predictably, end up warming to it - http://www.zdnet.com/dont-hate-windows-8-7000006297/).
Nope, this Windows is the first release that presumes/pre-empts that you, the user, will do your computing across multiple devices and that you don't want to have to worry about your data & user experience being tied to any one device.
Want to see it in action? Log into Win8 with an MS account on any machine - your apps, data, settings, everything will magically appear (assuming you've allowed it) even if the machine has never heard of you before (and again, assuming this isn't locked down). Load Office 2013 - again, your files & data appear as if you created them on that very machine, all completely seamlessly. All the apps & social integration stuff also follows you wherever you go - the idea being you wouldn't know you were on a new/different device - again all seamlessly streamed from whatever sources of social networking you have setup. That's huge; it effectively eliminates the concept of local file-systems for user data. Everything is transparently in the cloud and just works, as it should be. This is the first Windows to be built from day 0 on this basis.
Now, for people that don't like metro because they don't have touch? The answer is simple - don't use metro-style apps if you don't like them. Your old desktop works just as well (although it doesn't have the same level of cloud syncing) and all the apps you had on Win7 will work just the same way. If a killer game/app comes out in metro-style, guess what, you have the option to run that too. It would be like Mac OS users being able to natively load iOS apps if they wanted - the choice to be able to is good.
Not to mention the benefits for developers having a single & consistent API set to target every form-factor from multi-CPU gaming monster to WinRT/ARM tablet, and that's before we mention WP8 being as it is the same kernel. That's a benefit for users too; pick up any modern MS powered device from Xbox to tablet to desktop PC and the user will be in a familiar UI.
Also, keyboard shortcuts make up for any lack of touch. WinKey + X brings up the power-user menu; WinKey + C brings up the right-swipe bar; there's absolutely loads to help mouse/keyboard users feel at home, but there is a learning curve and from what I've seen from feedback, this is the most objectionable thing. People don't like change; bears have also been know to take dumps in the woods, life goes on.
Are you happy on Win7? Good for you; if you are on Win7 & have no other devices or intention of sharing data on anything but your trusty desktop, then frankly the benefits of Win8 are lesser.. There's a new & vastly improved task manager; Win8 is faster in almost all metrics, and there are some nice desktop GUI enhancements that you'd likely appreciate, however the face of IT is changing to one where it will be rare to have just the one computer, and Windows 8 has that front & center of the design.
One day your average IT worker will find the idea of saving personal data directly to a device actually most amusing I suspect, and the shift in thinking has already started.
There you go; that's my take on the best of Win8. I don't expect many here to appreciate it as I do but there's some real benefits in Win8, despite that being an unpopular opinion in the group-think echo chamber that Slashdot can be sometimes. Now lets return to the flaming.