I love the sexy new look, and until today I thought I'd be all over the new phone on release day, but after actually thinking about the features I think I may wait until my full-upgrade eligibility in January. In fact, the thing I was most excited about in this keynote was Netflix coming to the iPhone, and that should work fine on my 3GS. That and 4.0 will make my 3GS feel like a new phone, and I think that will tide me over until January.
The one feature that I was sure was going to pull me in for an early upgrade was iChat, which I expected to be able to use iPhone-to-PC and over 3G. FaceTime as announced is not a must-have feature for me.
In the end the iPhone 4 for me boils down to a hi-res screen, better camera, and gyroscope. I just don't think getting those features now is worth two hundred extra dollars to me.