As someone (probably here) once said, according to MS history, Win8 is due to be a bad OS. They've sort of developed this "every other" pattern when it's come to Windows operating systems that I've seen and experienced: Win95 was OK (but it was a significant upgrade from Win3), Win98 was a good OS, WinMe was horrible (2000 was OK, but used too much memory in my opinion), XP was wonderful (a great improvement from the Win9x series, including Me). Vista didn't really do as well as Microsoft wanted to, and was sort of pushed off, Win7 is a rock solid OS (frmy my experience, with a minimal number of annoyances, which there are workarounds for most of them), so I'm betting on Win8 being just another Vista.
The only people I can see who may benefit the most is tablet users or mbile users. But for everyone else, I don't think its worth the money (unless of course you get the free/$15 upgrade for new computer purchases--but even then so, I'd still wait at least until SP1 is released before I'll ever install it).
From what I hear, there is NO start button (that's been a thing that's been in every OS--crappy or good--since Windows 95). Plus, I'm not too big on the cloud-based stuff. I'm still old fashioned and like my stuff stored where I can physically see where it's stored (on my drives, in my home or work, not in some place 1000 miles away).
Ask me in a year or so, and I may have a different opinion, but as with most new software from MS (espeically OSes), I tend to hold back a little. I only bought Win7 3 weeks after it came out because there was a really good promo going on at MicroCenter, and it was too good to pass up (Win7 Pro 64-bit for like $110--full OEM edition). but I didn't install it until about 4 months later after a round of patches and updates were released.
Another thing is MS needs to come down on pricing, because Linux is getting more attractive as an alternative, and it pretty much doesn't cost a thing to obtain and install and use. In most cases, Linux is at least as stable as Windows, although not as easy to use (requires a bit more computer literacy to install in some cases, but overall, a good competitors to Windows).
Anyway, in my opinion, Win8 will have to wait for me. I may download the one from DreamSpark (since I'm part of their program through the local college), but other than that, I won't make it my main OS for at least another year, or until the next iteration of Windows (beyond Win8) comes out. Win7 is only 3 years old, and still has plenty of life left in it. They will continue to support it for at least another 4 years or so, at which time, the next version of Windows (Windows 9?) will probably be out.