Purely subjective, but
a) I haven't noticed any audio stutter so far. The litmus test will be installing a new application while listening to something.
b) mail is faster
c) upgrade process was easy. remove offending extras-devel package which prevented the update, update via application manager, re-install power-kernel, reboot. All working as before.
d) transitions seem to be smoother

ps Nokia really disappointed me with this update because I was expecting it to upgrade my N900 to four cores and 8GB of RAM