Having used my iPhone 4 for a few weeks, I can say that the so-called ‘death grip problem‘ is sadly a reality in my case. If I hold my iPhone with my hand covering the lower-left portion of the handset, the signal often drops by one bar.
Thankfully, this does not stop the phone from being able to make calls. I’m on the 3 network, which has in the past had a poor reputation for mobile reception but seems to have improved immensely; the only places where I have had no signal at all has been on the very remote parts of the railway line between Hebden Bridge and Burnley, and in a bar in Ilkley (outside the bar was fine). Elsewhere I’ve been fine, and in some cases getting a 3G signal where friends with iPhones on other networks have had to put up with EDGE or GPRS. I certainly haven’t had any calls dropped due to low signal.
I don’t yet have a bumper for my iPhone but did order one before last week’s deadline – that should be here this week and they are supposed to alleviate the reception issues.