I installed Windows 8 on my Dad's laptop and he loves it.
I'll begin by saying that I was sceptical of upgrading my Dad's computer to Windows 8, it doesn't have any touch capabilities though he did get the $15 upgrade promotion. He seemed pretty excited to get it and I decided that it's probably better he learns how to use it sooner rather than later.
I was honestly surprised. I kept going out and coming home to see him using it, and he's worked his way around it fine. He's still learning, but he loves it. The biggest thing is apps. I know Windows has had apps since 1.0, but not in the way we know it today and not as easily accessible. It opened up a new world to him. He downloaded the Kindle app and started getting interested in buying books for it, I told him about SkyDrive and uploading pictures to the web where he can access them anywhere and he was pretty surprised, he'd never heard of it before (he only just got his new Live account a few months ago, this is his first PC, he's had others, but they've been for work).
I wasn't expecting that, my Dad isn't exactly a Luddite, he's used computers for years and has always had he's blackberry but it's been in the bubble of his company. He's not exactly techie and doesn't understand everything completely but he gets it. Office is also HUGE for him, I wish people would stop playing it down. There is so much more you can do on Office that Google Docs will never cover. It's a professional standard. In fact the first question my Mum asked about upgrading to Windows 8 was "will the documents be compatible?" (between win 7 and 8). Google Docs might be enough for your average user, but I don't think many want to use it. Not at the moment anyway, I'm sticking with Office for the foreseeable future.
So to conclude, I was very surprised at his reaction and affection for the new OS. I think it makes things easier for him.