The servers are bound to be a bit busy. It's not as bad as an iOS update, but unless you're in some kind of special hurry, it should be easier tomorrow, or the day after.
Besides, you really should be making sure you've got good backups first.
That said, I'll probably spend the evening updating. I intend to do a clean update this time, so I'll probably still be adding stuff back tomorrow, and the day after.
First, I need to take inventory of my most used apps, and make sure they are either from the App Store, or I have all the necessary registration codes to re-install them.
Busy, busy, busy. Lots to do, even if the update isn't available yet.