At the very least, clear the cache. I have found that factory resets are by far the best and safest way to use an upgrade, but its not always practical to reset up your phone to just what you like. Clearing the entire system cache definitly helps get rid of the left over junk from the previous version, and certainly doesn't hurt anything.
(Cue the "I cleared my cache once, and then nothing worked" posts.)
(Cue the "I cleared my cache once, and then nothing worked" posts.)