I've been having the proximity sensor issue since the beginning, but I've never noticed the antenna issue because I have a case on it.
So I thought I'd check to see how MUCH degradation in signal there was, and not just with the bars, but with call quality and internet speed.
So I took the bottom part of the case off and did a speed test. First, without touching it. Good to go. 4 bars. Decent speed. Then I held it with my hand bridging the "gap." Speed test completely failed. Signal dropped to 1 bar.
So I hopped on Safari. Tried to load a page with the "death grip." No loading, nothing. Dead. I let go and immediately it sprang into action.
Then I called my home phone and listened as I talked into the iPhone. Crystal clear, sounded amazing. Then I bridged the tap. Without the slightest delay the audio disappeared. The effect of touching and releasing is immediate and complete.
My signal here in my office is 4 bars. I was completely floored by this little test. I was skeptical that the problem was so severe. Now I am completely and totally shocked that Apple let this phone out the door.
Having said that, I'm putting the case back on and using it happily. (except for the prox. sensor issue) But to know that I couldn't use this phone without a case is kind of disheartening...