Morale of the story is wait before you upgrade, you do not have to once apple says its ready.
My employers IT dept said to wait as there was a security issue that they wanted to/apple to, fix before leting the staff update their iphones (all 4S's) and ipads. No reported problems (well major or gripes) that I have heard of.
Some did not read the "memo: and went ahead, they lost there use of WiFi in the interim or got the phone taken off them until the fix!. That will make them look next time