I have seen quite a few people at my school using it as their main OS, actually. (Not too surprising, I guess, since it's UW and everyone here wants to work either for MSFT or Boeing.) I talked to a guy in one of my classes about it, I think with the first public build, and he said it was fine as far as beta OSs go.
I will hopefully be installing it Monday night. I just have to get a USB drive in the mail to create my recovery drive and then I'm jumping in. I'm not worried about it, but I have plenty of experience doing my own OS recovery/reinstall/do from scratch stuff. I tried 7 when it was in beta, and again with 8 and have done some sketchy MBR recoveries. My favorite OS recovery was after I managed to accidentally delete a file critical to the GUI and display drivers on 7
I think that if you know what you're getting into and know how to fix it yourself when it breaks, jump right in. It's called software for a reason. It's soft and malleable. It's easy to do permanent damage to hardware, harder to permanently damage firmware, and just about everything software-wise is reversible if you know what you're doing.
But if you aren't confident, stay away. It's good to have feedback from as many types of users as possible, but not at the expense of their system.