My new G4 phone does indeed drop calls if my thumb shorts the two antennas. It is a problem that could probably have been avoided, I have fixed the problem for me, with a small piece of clear duct tape, not sexy but effective. In other words I can live with it, because the phone is the least important use I have for the iPhone. It usually resides in my pocket.
I will surely get some form of protective case for it, but mostly because I really don't like the feel of it compared to the G3 series.
I won't be taking it back, the other features are way too good. GPS reception, is really improved, don't need the Tom Tom booster anymore.
You really should include the “stock holder” disclosure in your posts... ;^)