As someone developing for Windows 8, I have to say it's the best Tablet-OS on the market right now. It's very intuitive, fast, and has fairly few bugs (unlike Android). From a developer's standpoint, it is a dream to work with - far more than Android (terrible) or iOS (unless you enjoy Objective C, which I do not). From an end-users standpoint, I love working with the Surface tablet, I simply cannot effuse enough praise towards it's design, speed, and usability. I prefer it to Android (what I use the most), and iOS (what I use the least).
With that said.... Windows 8 on the desktop is broken, and is honestly a joke. It should be avoided if you already have a Windows 7 installation as it's design scheme seems to have been an afterthought. It is less productive, it is bug prone, many key features found in the latest releases of Linux, Unix, and Mac OS are still nowhere to be found. It's a complete waste of an upgrade and offers nothing worth the trouble of leaving a stable environment in Windows 7.
Personally, I find the concept of touch-driven desktop PCs to be silly, especially the greater we as consumers carve out a distinction between consumption computers and workstation/development computers. Windows 8 works beautifully when consuming content via a tablet or as a kiosk. In fact, I'm in the proof-of-concept stage of developing business software (a beefed up Point-of-Sale) specifically around the Metro UI. But, working with it as an everyday operating system on a workstation has been a chore. It never left my virtual machine because I simply couldn't justify the cumbersome and clunk user experience without any added feature-set whatsoever.
If you're tired of Windows 7, there are other options including Ubuntu (Unity), Kubuntu (KDE), or running Mac OS on your PC. Having used the latest offering from Microsoft, all the alternative operating systems are preferable choices to running Windows 8 on a desktop in my honest opinion. Either stay with Windows 7, or switch to something different - but avoid Windows 8.
*edit: Microsoft will likely address the issues with the first Service Pack release.. Until then Windows 8 may be the Windows 2.0, Windows ME, and Windows Vista style iterations that just get lost in history. They should not have combined the mobile and desktop interfaces.