I was among those very happy with 3G performance until I traveled out of New England last weekend. Somewhere around NYC 3G would show up strong, but nothing connected. It's intermittent, but in DC at least half the time I showed 4-5 bars and 3G and couldn't connect to anything, no email, no safari, just lots of waiting. Rebooting did nothing, but turning off 3G fixed the problem nearly every time (other time was at a Nationals game, I assume there was just too much traffic for any data to work well). I get better data service with 1 bar in rural new england than I did 2 blocks from the white house.
Anyway, it made me wonder if it's something about 850 or 1900mhz, perhaps one works and the other's wonky, or perhaps the network doesn't recognize the 3G connection some places?
No idea what the issue was, but boy was it annoying while trying to show large photos to a group, 3G would have been great but only edge worked. Heck, i'd even be happy if the thing switched to edge automatically if it sensed a junk 3G connection or it's the wrong wavelength or whatever.
Back in Boston now, and 3G is back to working beautifully. Weird.