I’ve had a bunch of hiccups with iTunes syncing and backup of my iPad (troubling!), and some strange crashiness that I haven’t narrowed down. Bartender doesn’t work, but in fairness I haven’t got around to checking to see if there’s an update or fix for that.
Surprisingly, my Apogee Duet has worked flawlessly, as have PopClip, Alfred, TextExpander, 1Keyboard and other utility stuff.
if you haven’t tried DP4, it’s worth a go — all the usual caveats and precautions, of course. I’m running it as my primary boot . I have an external Mavericks boot that I keep up-to-date just in case, but I haven’t used it in weeks, except to boot up and run updates.