Jelly bean is supposed to happen before the end of the year... yes its an improvement... as far as a big one... eh.... not really... it all depends on who you ask... jb is smoother...
I did the OTA..I don't think it's anything you're going to notice.. I don't.
EDIT... it could be coincidence, but all of a sudden I'm having data drops after the update... I didn't before....
Perhaps its the service in my area... but I doubt it...
I had the phone for a week and it dropped data 0 times in my apartment. Immediately following the Friday night OTA update, I've been dropping data every few minutes.