Hmm, when I hold my phone, I don't think my fingers or heel of my hand touch the bezel on the sides. But it definitely could be an issue for some people, I suppose.
I'm not great at math, so I'm not sure how much that would gain them, anyways. I do know that I hope the phone stays pretty much the same size. Then again, I've had my 3GS for so long, I'm just totally used to it at this point.
It feels like I've been waiting for the iPhone5 to come out forever.