I don’t have one yet. Based on what I’ve read, I don’t really need one. The 3G network is nicely fast, when you can get it to work. I’ve read about a lot of people being surprised (disappointed) that 3G doesn’t seem to be in effect in their area even though AT&T’s map says it is. I don’t need that.
I know it’s “only” $200, but I’d still have to go to the store to get it, AND the service plan costs more ($10 more) per month. If I didn’t have an iPhone already I’d run out and get the 3G right now. But since I already have one… I’m in no hurry. The old one, once upgraded to the 2.0 software, is just as capable.
Advice: watch for used first-edition iPhones on eBay etc. I would guess that you could get one for $100.