Metro
I have to say, I *can* live with Metro and the new Start Screen thingy. I certainly will not love them, though that may come later -- Stockholm Syndrome, maybe...? -- but I can live and operate with them.
Let me first make clear that this is preliminary based on a few hours worth of testdriving the Consumer Preview with emphasis on UI usability and might change once I sink my teeth into this Release Preview, but:
The command line is largely the same, and there still is type-to-search functionality when one presses the Windows key and starts banging away on a keyboard. And I honestly cannot remember the last time I opened a Windows 7 Start Menu and clicked on it with a mouse. So Windows 8's user interface is, for the most part, compatible with the way I work day-to-day.
What will decide things for me is (as usual, I think) the technical stuff: how will it perform? Will it be stable enough? What new features will work how well? Etc.
Speaking of new features, Server 2012 looks rather sexy, I must say...