I upgraded my iPhone 4 to iOS 4.0.1 and, big surprise (not), it still can't make phone calls if I'm holding the thing in my left hand using the kung fu grip of doom (i.e. the normal way I hold a phone). And, unsurprisingly, my 3GS still can make phone calls with the same grip in the same location.
I ran the Strength App, which we've discussed in previous posts about the iPhone 4 antenna issue. It is now showing a more nuanced level of how bad my home reception really is, but the bottom line remains the same. If I put on the Bumper, the thing can just barely make calls. Without, it can't.
The iPhone 4 just isn't a very good phone in low signal areas, which unfortunately is where my home seems to be. The difference is that my old phone never had a problem with those same signal conditions and my new iPhone 4 is crippled.
I know that Apple intended its update to change expectations -- fewer bars indicating less reliability -- but my expectations are that I should be able to make and receive calls in an area where I have already been doing so for the last three years, with Apple-branded equipment.