It's bearable but I'd wait until the update is released. I've had issues with Mail, Finder, iTunes, Maps, and Activity Monitor. Some issues were fixed with a reboot, but my philosophy is that I shouldn't have needed to reboot to begin with.
My machine WAS running fine after the upgrade, but lately has been slower which is what concerns me (these issues also recently started too, a week or so after the upgrade).
All in all, you should be "ok" if you upgrade but I'd wait until 10.9.1 to be safe, assuming Apple fixes the bugs.