Lucky you. I'm in the UK and the areas where I got full 3G signal on my iPhone 3GS I now get GPRS on iPhone 4! Not even edge! Not happy.
That's interesting. I was using my friend's iPhone 4 outside yesterday and no matter how I held it, the phone just couldn't get anything beyond GPRS, even with full signal. However, when I placed the phone on a table (and didn't touch it), it got 3G very quickly. I picked up the phone again and it went back to GPRS. I doubt that's coincidence as it's very easy to replicate.