I am the unwilling recipient of Windows 8. Lenovo couldn't fix the new Windows 7 Ultrabook I bought, so they sent me a Yoga laptop, with touch-screen and Windows 8.
Once I bought a start menu replacement, I don't mind Windows 8 too much - it's ugly, but most things work as well as Windows 7. But the thing that drives me crazy, endlessly, is the virtual keyboard popping up when I'm trying to do something else (well, just about anytime, since I almost never use it to type). It's like a giant Clippy that covers half the screen.
I haven't figured out what causes it to pop up. It seems pretty random, and sometimes it goes away before I can even reach for the escape key. Sometimes it comes up when I'm typing, sometimes when my hands are nowhere near the keyboard. Sometimes several times a minute, sometimes not for hours.