Microsoft should learn from Google I/O
Google's Android Ice Cream Sandwich and Jelly Bean are obviously inspired by Metro UI. And while it's not as extreme simplistic as Windows 8, there are some things I really wanna see in Windows 8, such as VERTICAL SCROLLING.
But the most important problem Google has solved is to provide a simplistic UI without making your eyes bleed. In Windows 8 you have these strict, "lollipop" colors while Android uses transparency and gradients that are calming to the eye. I also think there should be an omni/search bar on the Windows 8 lock screen.
And then there are things I don't want to see such as the old-fashioned icons, the ugly widgets that just feel out of place, the ugly onscreen buttons that you can't hide.