Nah, its not that buggy. Sometimes it takes a while to start up though. The Metro UI bar on the top is buggish because of the blue outline, and there are some cool effects!
BTW according to winbeta.it and BA, it has been leak. But dunno is it origin or not. Can we confirm on that?
yes it has been leaked but it's full of bugs!!!! my personal advice not to download that crap (atleast now)...wait for a better build with minimum bugs
Thanks for the warning, other have said it will not will not install in Win8. I'm lucky to have 4 different HDs to try it on, with backup images of all.