Honestly, I hope that, after looking at all the lukewarm reviews, they decided to bring back the start button. (or at the very least, make the metro start menu more intuitive - hidden controls aren't obvious by any stretch of imagination) If they've fixed it, I just might upgrade. Otherwise, I'll be on Windows 7 for a VERY long time...
Note: I don't hate the idea of a fullscreen start menu. I DO, however, hate unnecessarily hidden controls (start screen, shutdown, search - I know you can just start typing at the start screen, etc). Heck, after using 8 on a desktop/laptop for a while (just testing it, still using 7 otherwise), when I used it on a tablet in a store, I couldn't get things like the charms bar to work. I later found out that on a touchscreen, it's a different gesture. So much for being uniform across platforms... The other issue is that I don't want it suggesting ANY tablet things when I search on a desktop. Period. (for instance, search 'windows update') Metro adds NOTHING (aside from a few sorting features on the start screen) for desktops and laptops, and purely gets in the way. Had Microsoft put in a simple option to disable metro, I (and plenty of other people) likely would've upgraded by now. That's all revenue Microsoft chose to throw away for the sake of needlessly shooting themselves in the foot...