I pre-ordered and picked mine up on launch day. The phone itself is beautiful, a lot more weight to it, it "feels" quality but is likely just the bigger battery. Facetime is cool but I wont use it much since you have to be connected to wi-fi and I typically am not. Tethering only allowed if you bump down from unlimited to 2G data plan which as I mentioned I dont use wi-fi often with it so that isnt an option for me. Screen and camera quality are amazing.
Ive had issues with the sim card. I keep getting intermittent Sim Car not installed errors. Research says fixes range from, reboot, toggle airplane mode on and off, toggle airplane mode while also toggling wi-fi on/off, plugging it into a charger, to removing and reinserting the sim card. I have had this issue come up 4 times today alone.
I also have noticed that although the screens supposed to be pretty tough, it has actually already scratched VERY easily.
Part of me wishes I went from 3G to 3GS and avoided the initial batch of the 4. But it is what it is and over all its a great phone, better once the bugs are exterminated.
-Lou