Yes, the UI, now formerly known as Metro, is annoying, but it's avoidable. I've used Windows 95 through 7, Ubuntu, Slitaz, Mint, DSLinux, and OSx Lion (unfortunately). I prefer Linux, but Windows has DirectX. Windows 8 is just windows 7 with tablet support, virtualization, and sync with the "cloud".
I've forced myself to use Windows 8 as a main OS for over a month now because I will probably be able to get windows 7 free through DreamSpark before the Release Preview runs out, and I'd like to save $140.
I have found that with not much effort, the "Metro" apps can be removed from the start menu completely, and "normal" apps can replace them. One metro app I've found to be quite nice is the Hotmail app. To check my email all i do is press the windows button on my keyboard and click the mail app. Other nice additions are the integrated Virtualization/Hyper Visor, integrated image mounting, better integrated archive management, VERY fast boot time on an HDD. The task manager is a little better, but I still prefer other programs. The right click function for apps in the task bar has improved and I like it quite a bit.
My favorite parts of Windows 8 are the searching and the sync between different computers. Searching involves tapping the windows button then typing, and its full screen and incredibly fast. As for syncing, your Live/Hotmail account can be used as an account for the OS, so as soon as I log in on my laptop, Everything except for specific hardware settings and desktop shortcuts are the same. This combined with google chrome's sync turned out to be awesome, even though I really didn't care.
Will I upgrade to windows 8 when it releases? No, but I "might" after all the bugs are fixed if it's cheap, which it won't be.
Windows 8 is just Windows 7 service pack 2 with tablet support. I don't understand the hate. The new UI is very easy to ignore, and can easily be used to your advantage.