In today's case, the store opened at 8. I went over at 9, hoping the line wouldn't be as bad as last year. I was right - it was worse. I finally got into the store a little before 2PM (!) and the actual purchase was relatively pain-free. The payment systems at Apple were up and down much of the day and that slowed them up even more. Apple was activating phones for people who wanted that - I just wanted to get home by then (I was starved and tired), so I got in, backed up my old iPhone (which was deactivated already) and, after a few tries I was able to get the phone activated. Restoring took about 15 minutes, and I had to re-setup my voicemail because it was lost in the transfer. All OK in the end, though.
UI performance is slightly more responsive than the original. The hand feel is a little better (it's tapered now), and the volume is much better on the speakerphone. The 3g radio is significantly faster. You can tell. Other than that I'm still getting the hang of it.