I have a 3GS and my friend has a 3G. A couple of weeks ago I had zero signal and he was standing right next to me with 5 bars on his signal. I also experience a loss in signal and switching the phone off and back on again is the only way to get the signal back.
+1 to this IME, but along with clubber and co. I'm no fanboy for Apples, but love my iphone and wouldn't be without it, owner for 10months.
As for rugability, mine has a outer case and screen cover and lives in my trouser pocket full time (along with everything else I can stuff in there) and in the backpack whilst riding and is definitely not treated like the treasure item, that it is to me, yet no damage.