My personal experience:
I was using windows 7 on my home computer and was happy with it. When i upgraded this fall(new mobo and all that goes with it) i decided to give win 8 a try, for no other reason than getting some hands-on experience, since at work i am taking care of some 90 or so computers and sooner or later i'll have to deal with win 8 on them anyway.
On my home machine, I installed win 8 on a separate SSD, leaving the original system drive with win 7 intact, so i can now choose which drive to boot from and switch at will.
The first impression was not so good, it took me over an hour just to get my bearings(discovering where all the familiar things like control panel and desktop went). However after i customized the metro 'desktop'(which means i basically threw out everything and the starting w8 screen has only three tiles: 'my computer', email client and a browser) i came to like the new OS. The main thing: it's blazing fast compared to the w7. Press the power button, and the comp shuts down before i can count to three. And the w7 is on an SSD as well, mind you, still it doesn't come close to w8.
So now i'm using the new OS. The only thing that irked me originally - the inability to go directly to desktop skipping the metro interface - turned out to be a non-issue, since in w7, the first thing i usually did was to either fire up email or the browser(which involved clicking the respective icon), and in w8, i'm doing the same, just the icon is the metro tile(clicking firefox tile in metro automatically starts the desktop then starts the browser in it, and closing the browser you stay on desktop).
All in all, after the initial shock, the experience is positive. It's faster, and i'm discovering some nice perks like the new task manager etc. Very few negatives as long as i stay on the familiar desktop(minor stuff like clicking on network icon in tray pulls up a huge metro-style side panel that unneccessarily takes up screen real estate etc.)