I'm aware it's not an universal problem.
I think the "problem" has become a lot larger than it actually is on a worldwide basis because of Apple's silly exclusive agreement with AT&T, whose network is widely acknowledged as "sadly lacking" in many aspects. I was a victim of that for about 2 weeks. Poor connections, dropped calls, no signals, etc. And I wasn't even on an iPhone.
Of the four iP4s I've sampled, two of which are mine, the other two also did not have problems. Those other two were from an earlier production run. Ok, the sample is very small but that's 100% pass rate.
I suppose we'll see if the above remains true after the local launch and the iP4 is in widespread use.