I've not used Windows 8 and I doubt I will in any near future. I don't se any applications nor play any games that require such an operating system.
It seems that Microsoft is considering (or already has in place) not providing any more retail versions of Windows 8 and is only allowing an upgrade to Windows 8 by DVD or download.
This is precarious as it interferes with the previous version OS (Windows 7 x64) and may cause BSoD's.
Links -
http://www.slashgear.com/microsoft-windows-8-retail-may-be-axed-entirely-13238498/
Windows 8 is designed for tablets and touch screens so unless you have a touch screen, it might be rather ccumbersome to use (until you get the hang of it).
Sure, it is faster boot times but there is more to a PC than just booting up!
Actually, although I have both Windows 7 x32 and x64, I prefer to use Vista x32 with IE8, had nothing but problems with IE9. Firefox for Vista was good with my laptop until ny hdd carked it. Most games I play are pre 2007 and I use my souped up Windows XP to play them.
There are problems associated with using an upgrade OS, it might not be suited to the PC (or portable) that is being upgraded, the motherboard drivers might not be available, and not too many applications are available with Windows 8, you'd also need to upgrade any apps you had installed, as well.