I've been reading the Eight Forums a bit and it's rather testy over there. Apparently there are some very strong differences of opinion about Windows 8. The comments seem to be very polarized: either you really like it or hate it.
One of the bigger complaints I see is that the Start menu is gone. Microsoft is trying to change the paradigm of the desktop yet again. Is it worthwhile? I think that depends...
Some people are citing that changes made are gearing up for the metered software use policy that Microsoft has been hinting about for the future. In essence, you would use their office productivity software billed by the hour instead of paying for a one time installation license. I personally can't see that ever working. People are so accustomed to paying for software once. If Microsoft pulls this billable by the hour method, you'll see plenty of people switching to Open Office. For those who still want to save a document as a true Microsoft document type, they'll do all of their preliminary work in another product, then copy/paste it into the equivalent Microsoft product for final editing. Just dandy!
Anyway... all that aside, some people have reported W8 is more efficient than Windows 7, but by exactly how much I'm not really sure. W8 has modes for smaller devices like tablets, so it would have to be battery friendly. If it's a dramatic power improvement where a typical laptop that gets 2 hours per charge would increase to 3-4 hours, then that would be a welcomed improvement.
So, are you happy enough with Windows 7 that you won't make the move? Or is W8 looking attractive enough to you that you'll upgrade once it is officially released?