I upgraded.
I have been doing a whole bunch of things that haven't required me to push the limits yet, but so far, I am just as happy as I was before.
Auto-upgrades, they changed a bunch of stuff around, so all the short-cut keys and a bunch of menus are different, but nothing that has left me thinking I made a big mistake.
Somethings, like saving out in different formats are better. Auto-save is cool and does different back-ups instead of just the last one it did, so it'll save your versions for you.
But like I say, I haven't pushed it that much yet.