With as much of a bad rep that 8 had gotten, I expected to hate it, too. But once you get a good start menu, I've only got five small complaints, and it starts up so fast that it's worth it to me. I don't even have an SSD for the OS and it's starting from off in only about a minute. <15 seconds from sleep, 20 seconds from hibernate.
The five small complaints are:
The windows maximize if you try to move them off screen slightly, horrible idea for a shortcut. (although, I think I remember this feature from Vista or 7, I'm going by actual complaints, not just new stuff.)
8 goes overboard on the "is not responding" thing, where it used to be a telltale sign, it's now a lot less trustworthy.
Menus will pop up if you move to the far sides of the screen, but I never use them, never want to use them.
Changing the multiple log in pictures is annoying.
When actually starting/restarting the computer it goes straight to the Start Screen.
If 10 can fix those things, actually do intuitive things, and maintain the speed, I will be pretty happy. (although, I know I won't upgrade for a long time)