I was upset about the new UI until I realized I don't actually use my start-menu OR my desktop anymore. Everything is 'Windows' Key - type, enter... i don't even look anymore. That or quick-launch bar, which it seems METRO is just bigger. So in a way, I'm already using Win 8...
All that said, its as if all the haters are sitting there all day starting at their beloved desktop screen. This is confusing. Beyond the few seconds after I sit down, the only thing I'm looking at is the applications I have running. If Win 8 can run those faster, and utilize my hardware better, then that is all that matters. The UI is not the OS- its the guts that count.
Ultimately though, no one will really care, once the device unification benefits are realized.
my 2c..