For me, F14 was the last good version. F15/16 crash (F15 was so bad X wouldn't even work). F16 became mostly stable after dropping the use of NetworkManager. It seems to do ok when there is only one network interface (wired or wireless), but useless when two or more - It couldn't seem to figure out default routes at all, even when told. Systemd can't seem to get booted properly, much less shutdown (F17 wouldn't shutdown, and F16 has issues if a VM won't shutdown).
And the excuse that systemd allows for fast booting is shown false, as a Slackware boots in less time. The included SysV init emulation isn't an emulation (it just isn't capable of providing the proper ordering).
And the interdependencies caused by systemd, dbus, and udev are a real puzzle.