i've been using 10.9 since beta 4, and i've had nothing but stability. its actually surprising, considering how many complaints i read about safari crashing, graphic glitches, slow performance, etc.
in fact i have some unapproved mods to my 13 inch macbook pro so if anything my system should be the one thats unstable. Replaced my hdd with a ssd. replaced optical drive with optibay second hdd.
admittedly the ssd makes everything faster, but usually beta bugs are bugs, and thus even a fast hard drive can't combat them. I have had safari super stable. fast. no issues at all.
Just updated to dp6 and again, smooth as butter.
The only issue i have had on 10.9 is one safari crash, viber app wont work, and one computer restart for some reason (i wasn't there. i just noticed my macbook had restarted).
I did a clean install of 10.9 btw. again, from the initial forum posts it seemed that if you did a clean install people were having a lot more issues than an upgrade (which is surprising to me).
my computer usage has been very basic though except for lots of safari tabs (12-15 generally). i use ms office, and the usual suite of communication apps (eg skype), entertainment (itunes and rdio), acrobat pro, etc. but nothing graphically intensive or hardcore like photoshop, videos, or multiple monitors.