i’ve been using 12.10 for two days now. i haven’t noticed much difference yet besides the following:
kompozer has been removed from the repository (possibly because it doesn’t seem to be maintained)
some application launcher icons on the gnome classic panel are not being displayed properly (size scaling of the icon is off)
gnome’s archive manager is crashing randomly when i attempt to use it. i imagine this one will get fixed soon.

those are all negative items. a positive item is that chromium has been upgraded to a newer release and appears stable. the last chromium update in 12.04 caused the browser to randomly crash for me.

update 11/5/2012:
installed system updates today that seem to have resolved archive manager crashing. evidently this was an upstream gnome issue.