For me, yes, I can afford the extra $10, but I can't justify it as I don't use the data plan all that much for the price I'm currently paying for with the 1st gen iPhone. The EDGE network is just unusable given its current state.
To give it another perspective, people are paying much less for broadband access (cable/DSL) for a faster speeds. So, ATT is basically saying it is OK for you to pay $64/month to run a crippled iPhone or you pay $75/month to have a better iPhone experience and a 2 year contract. Gee, thanks.
Yes, I know one pays extra for convenience, but I believe there is a line for some of us and ATT just crossed it. I've been a long Cingular/SBC/ATT customer, but this one was the last straw. I'm dropping my DSL service which I've had for almost 9 years. I, for one, will boycott buying a 2nd generation iPhone from ATT. If anything, I'll find other channels to get one.