I'm going to upgrade as soon as I can. 3G connectivity here is fine, but things like typing lag, application crashes, battery life, and backup time need to be fixed.
I have all of the issues you mentioned, and then some. So 2.1 is supposed to clear all of that up? That'd be awesome. I want to wait, so I can use Installer and Cydia. The only reason that I still have the iPhone 3G.
I did tests like using my Treo 750, and got 2 bars in a specific place, and then swapped the SIM out to see how different the reception would be on the iPhone. It was searching and searching and searching for a 3G signal, and eventually it "settled" for 2G. I made a call, and only 2 minutes into the call, the call dropped, as any 3G phone obviously looks for a 3G signal whenever it is not on one. The call dropped, and it was again, searching and searching and searching, and actually found one. 1 bar. 3G. Wow. NOT! I made the call to the same person, and this time it took only 45 seconds before it dropped again. I disabled 3G in Settings to force it on 2G, made the call to the same person, and it didn't drop again.
I can't work like this. So I'll use the SAME spot, and do the experiment over to see if there is any difference when I load 2.1 on it. There had better be one. Otherwise some poor soul will be the new owner of my iPhone 3G. 3G... lol...I call mine "iPhone 3G, sometimes". And 2.0.x has been beta software, at best.
WiFi isn't any better. I can never have multiple simultaneous software downloads. I can set my watch to it crashing if I don't do them one, MAX two at a time. Then, although I have a lightning fast 802.11n network, which works as a G network, too, of course, and a FULL bars, just drops the connection out of nowhere for apparently no reason. The iPhone 3G, sometimes, is not good at WiFi, even at FULL bars.
I really want to keep my iPhone 3G, sometimes. It's such a pretty device. And I have a lot of bases for comparison. My Blackberry, and Treo, being the main two devices, besides my iPhone 3G, sometimes. And they will both see an upgrade this month. Blackberry Bold, and Treo Pro.
2.1, you're my last hope. If I want a device that looks as pretty as the iPhone 3G, somtimes, I'll get the iPod, the one with WiFi, so I can do what I do with my iPhone now, which isn't much.