I like the performance increase, and SSD is easier to use with Windows 8. I appreciate that.
I am not happy with the start menu--from a functional point of view. If there were pros to it, I'd have no problem, but there's no merit to the direction they're going with it. It's a small part of the OS, and they can EASILY support both.
I usually press the start button, type what I want, and press enter. That still works and that's good (except when it includes something on my data drive, which isn't currently spun up). But when I want to see my system tray from something covering the start menu, it's a convoluted process to do so. When I want to spend several seconds looking through a list of things I typed in, I don't want to use the whole screen to do so. Shutting down the computer is convoluted too, so I just use alt-F4 on the desktop.
You don't have to interact with anything else in windows 8 that's different from windows 7 aside from this. If you can put up with this (I do, without getting too upset, except when I have to talk about it), then do it. But bottom line is, they removed functionality.