Here in NYC I've found that 3G speed is all over the place. I'll also have to side with Dan as an EDGE defender- I've had pretty good luck with it, often getting speeds in the neighborhood of 200kbps, which is perfectly usable, especially if you stick to sites that are more low-bandwidth friendly.
I've found 3G to range from blisteringly fast - indistinguishable from wifi - to really slow - slower than EDGE in a number of locations. I almost always leave 3G turned off, due to the power issues. Fortuntely, I have enough wifi access so that this isn't a big deal.
3G is certainly no bandwidth panacea..