I've been running Windows 8 since RTM, and I'm convinced that the people who say they don't like it are the ones who really didn't bother to learn how to use it. Your workflow is partially disrupted for about 2 weeks after you get over the idea that you no longer have a start menu and you use the Charms bar (as one of the many ways) to shut down, but after that you don't have any issues. Windows 8 is significantly faster, and most report better frame rates in games. It takes me ~10 seconds to boot, and I prefer booting to the Start Screen interface because I instantly see my notifications (email, calender, weather, etc).
After learning how to use it you will seriously never understand how you once preferred anything else. It just makes sense. The start menu has been a cluttered cluster**** for years... a hundred different folders and subfolders and subfolders... it's pointless. All of the best bits from the start menu are still available too-- just right click on the start button in Windows 8 and you get this:
Very simple and straight forward.
A lot of people say it's a bad move etc but so far, all of Microsoft's moves have been great (Windows Phone is a great OS, it just lacks apps, the Surface is a great tablet, and Windows 8 is well polished).