As mentioned in other threads, my wife hated Win8, so I put Win7 Pro on her laptop.
But seeing my Dad use Win8 was enlightening... He's no technophobe, he started with computers using IBM Mainframes in the 70's and desktop PCs right through the 80's and early 90's. But in the mid-90's, due to change of work and not needing one at home, never bothered to update/keep up. Mum on the other hand basically just knows enough to be dangerous, and is happy with XP. (she basically only does web/email). But back to Dad, he admits he's a new computer user in the modern age, so ran through the experiment from a new computer user.
His take on Win8 and the Modern UI, he was happy with it and understood the basics with a 30min tutorial. He thought it was easier than WinXP, as everything was on the Start Screen and could access the Start Screen with the Windows key was very helpful. Overall, he thought the workflow presented by the ModernUI and ModernUI based apps was very easy, since they were basic and did the core of what they needed to do. All functions were available from a right click if you needed something more. His only complaint with ModernUI Apps was the lack of a close button, but showed him that to close an app was ALT-F4, or alternatively if left running as available by mousing to the top-left of the screen.
What I observed was the reduced functionality of most ModernUI apps actually helped new users to be productive in a shorter time period as they weren't over whelmed with cluttered screens. In a sense, I think the MS people did a very smart thing be bring the core applications people use back to basic functionality, and as they say 80% of people only use 20% of the functionality... (And this is the reason why people bitch about the ModernUI apps, is that they use a different 20% of the functionality).
So his take on Windows 8 - very positive for a new user to computing.
What I noticed was that if you stuck in the ModernUI eco-system it all worked extremely well, and the entire OS felt very integrated together even with 3rd party applications. But once you left the ModernUI and had to move between traditional desktop and the ModernUI, it broke down pretty quickly especially since it all lost the integrated feel.
What did I think of Windows 8 - well my judgement hasn't changed of it... It's just Windows with a tiled start menu instead of a start menu. More blah... (The one item I did like with the tiled interface, was that the Mail tile had the number of unread emails visible and a few of the other apps had their status immediately available/viewable from the Start Screen).
He also got a new MS Mouse with the touch area in the scroll wheel position, and that had gesture support and it also integrated well with the environment.