Ok, I'm 3 hours in, and 2 since I stopped driving and could play a bit. I'm loving the bigger screen, and it feels even lighter than I expected.
The screen's contrast really is better, and so is color saturation. The white balance on the 4s always seemed a little off to me, and pictures from the 5 so far seem to have a more accurate image. I'll have to play with it more and do some side by sides to see if that is real or imagined.
I'm out of LTE coverage area right now, but I'll update when I can compare speed test results vs. Verizon here in the Portland area.
Definitely not a disappointment in any sense (except for crappy service from AT&T this morning after 8 hours in line.