I upgraded to 3.01, but not for any particular reason. I guess I was sort of hoping they'd secretly add in an option to undo some of the visual changes that I don't like (eg. Friends List and larger font). Of course that wasn't the case -- oh well.
Other than that, I wasn't having any problems with 3.00. As far as I can tell, 3.01 is also working fine. I have a launch 60GB model PS3.
As for Uncharted, my friend who also has the same PS3 as me (we bought them at the same time) hasn't had any problems and he had recently started playing it all the way through to try and get a platinum. I'm not really sure what the magic combination is for problems, but he first played Uncharted through back when it was released and then just started playing again as of 3.00 (and now 3.01).