I picked one up on launch day and love it. Moki has hit on all the major points but I'll reiterate what he said: try one before you knock it. I have yet to hear a bad review (other than minor issues that can be fixed through a software update and complaints about there being no GPS or 3G). Overall, people who actually used the phone love it.
Is $600 expensive for a phone? Sure. But I'd argue that $50,000 is expensive for a car too, because I can get a good car for less than $20,000. Problem is, it won't have the power, handling, design, etc. of the $50,000 car.
Kia vs. BMW. No different than a cheap Nokia vs. iPhone.
With respect to AT&T, I've been a customer of theirs for over a year and have never had a dropped call and have service everywhere I have travelled. They are no worse than any other mobile carrier IMO. I get reception places where T-Mobile showed no service and I'm sure T-Mobile may have reception places where AT&T may not.