Bear in mind that most reports will be coming from the States, where the iPhone has always been absolutely crippled by the AT&T network which apparently has terrible coverage, poor speed and regularly drops calls.
They only recently got MMS there and still don't have tethering AFAIK.
That's been cited as one of the main reasons that Android has overtaken iPhone in the States, but had slower growth in the rest of the world.
It's also the main reason they put a huge BFO aerial in the 4G.
In the UK I generally get pretty good coverage on O2 and I wouldn't say I get more dropped calls than any other phone I've owned. Though I will admit that sound quality can be a little but crap at times, especially if you keep moving the mic away from your mouth like I do.