Overall, that was huge. Biggest iPhone software release aside from the release of the App Store. Period.
Multitasking, I'm going to get some use out of it. I could live without it easily, but I'll probably end up using it.
App folders, holy cow. I've wanted this for a long time, but I never considered folders. No longer will I need to have one page for each type of application.
Game center, I'll need to hear more on this. No idea what it will be like, but it appears to be Apple's answer to console online services.
iAd, it's about time ads didn't suck.
Won't work on iPod Touch 1st gen, I'll need to buy a new iPod Touch.
I think this completely knocked out a lot of the things people were bitching about being wrong with the iPad, iPhone, and iPod touch. Except Flash. Flash sucks.