Without commenting on all the other posts, I will just say I agree with the OP.
It's the best ipod/handheld computer I have ever used and the worst phone I have ever used. Whether or not it's Apple fault or AT&T's, the bottom line is I was dropping >50% of the calls I made. That is unacceptable for a PHONE! So there is now one more IP4 making it's way through the system to the used/refurb/insurance replacement supplies.
It's to bad, I really liked every other aspect of the iPhone 4, so maybe the upcoming new ipods might be the ticket for me.