Fedora uses the excuse that it is bleeding edge, but it is no more so than Ubuntu. Both have a similar aggressive release schedule and both have similar backing and similar approaches, to push the envelope. The big difference is that when something is wrong in Ubuntu people blame Canonical for making a mistake, but people make excuses for Fedora, saying it is bleeding edge.
Adrainx says he expects Fedora to break, but likes it anyway. This is akin to Windows users who use a broken OS knowingly and excuse its faults. Why would anyone choose to use a crippled system when they don't have to.
I have many distros installed. Fedora 10 is one of them, but I keep going back to my main distro which has never let me down for my main distro. It is Ubuntu 8.10. I have run Ubuntu since Feisty and have installed alphas and betas in that time. I have experienced crashes of individual applications, but I have never had the OS become unstable and unusable.
I have had Fedora 8, 9 and 10 stable releases break and become unusable. That is the difference in my mind. Most guilty for breakage is poor package management. When apt breaks, the fix is easy. When RPM breaks you are basically pooched. It is not as bad as in the past, but that is far from making it good.
I am very hard on package managers. I install every desktop, window manager, piece of eye candy and multimedia codecs and restricted driver that I can. This is partially intentional. I like to see how far that things can be pushed. It is also that I don't like being restricted in what I can install, so I install to find the limitations. Every distro is different, even ones using the same management system.
The worst is OpenSUSE. I can break it just doing updates. Its resolve dependency dialogues frequently only compound the problem. Breaking Fedora is a little harder, but it is easy to do. I do updates and then keep adding packages. It is just a matter of time. The hardest RPM distros to break are Mandriva and PCLOS, but they can break, too.
I can break Ubuntu in the same way. The difference is that Ubuntu is easy to fix both from the commandline and from Synaptic with the fix broken dependency selection. It is simple, straightforward and it works.
I deal with my own experiences in using Fedora 10 on my blog at
http://linuxcanuck.wordpress.com/2008/11/30/an-ubuntu-user-takes-fedora-10-for-a-test-drive/
I am not self promoting here. I just don't want to repeat myself.