Even though, I found some bugs, it was not so bad. I don't have any problems to use Wifi connection, sound, using dual monitor, video card. So it will meet require for my daily use. I think it is not bad idea installing F15 when Alpha is released. Of course if there is no critical bugs for me :P
However, I usually use rawhide on kvm so that today is the first day of using Gnome shell :) My first impression is "that looks cool !". I have used some desktop environments such as Gnome, KDE(long years ago), jwm, fluxbox, Windows7, Windows Vista, MacOS X and so on. though, it is the best looking I've ever used before.