Bars dropping as soon as I pick it up... not good..
Mine was delivered to Preston by TNT just over an hour ago.
The screen is great but there is definitely an issue with signal strength when you pick it up. As somone else pointed out, if you hold it in your left hand so that the bottom left part of the phone sits in your palm, the signal strength can drop from the full 5 bars to nothing and the call fails. If you hold it in your right hand there is no problem. I also put the phone into my 3GS silicone case (which is too big for the iPhone 4) and the problem does't happen at all, even when held in your left hand. My bumper should arrive shortly so hopefully that'll prevent the problem occuring.
There is clearly a problem if any part of your body is in contact with the metal rim at the bottom left of the phone. There is no way that it is just a software issue / issue with the display as the problem actually causes calls to fail, despite the fact that I'm in a very strong reception area.
I can live with the issue for now as I'll use a bumper but I can see a mass exchange of phones having to take place over the coming months!