I upgraded a week ago and it seems to be a bit 'jumpy' at times, though only on certain websites and perhaps because of various plug-ins showing featured content etc. It also appears to be slower than Safari 4 in loading pages so far. I realised that after reading what has happened to many other users, that my niggles are small and i should be thankful
As always the first versions are 'buggy', so as the previous poster did, maybe switch to Firefox/Chrome for the next few weeks until they sort out the bugs. Chrome, although good leaves me uncomfortable with the amount of info that the "do no evil" company uses from browsing.
SHJ