I got the remind-me-later option at 1 a.m. I clicked it and my phone waited approximately 7 hours before it ran the update for itself. NIce, eh?
At any rate, I haven't noticed any problems after the update. So far, the phone is running great - better than it was before the update. (I had noticed that it was becoming a bit sluggish.) My news widget disappeared during the update, but it was still on the phone. I think they removed the Yahoo news widget that was pre-installed. It had stopped working anyway. My photos, books, contacts, music, etc. are all still in tact.
My email widget prompted me to do manually refresh all of my accounts after the update. I think the keyboard may be a little different now. It also clicks when I type. I haven't figured out how to turn that back off.