Well I updated, but it's really mixed for me. I REALY liked my 3GS, and figure since I liked that one so much I would like this one even more. Really, it's about even for me. With the 4 I get a really nice screen, awesome camera, faster everything, and way better battery, but I lose the 3G design (feels way better in my hands, and seems a lot less delicate than this new phone) I have a proximity sensor that hardly works, speakers that aren't as loud as my 3GS, and if I hold the phone a certain way it can cause me to drop a call. Would I still have upgraded had I known all this before hand? Hard to say, but probably yes.
The biggest issue for me right now is the proximity sensor. God it's annoying. I'm hoping a case will make it easier for me to hold, fix reception issues, and also make it more durable. I'm also hoping the volume booster jailbreak app will make the speakers louder so I can enjoy my music when I'm
at work.
That's really all I can do, because I can't return it because there is nothing at AT&T I want and I can't switch providers because my gf loves her 3GS and won't give it up, and I can't go back to a 3GS screen now.