After hearing Apple announce that you have 30 days to return the iPhone 4 without a penalty, I decided to buy one on Friday. Of course I picked up a bumper with the phone. Unsurprisingly I was easily able to drop my signal completely by holding the phone the normal way I would in my house. So I put on the bumper and did some testing. Contrary to what many sites are reporting, what Apple says, and what many Apple fanboys will suggest, the bumper cases DO NOT completely "fix" these reception issues. They do dramatically improve the problem, but on several occasions over the weekend I noticed that when I was in a weaker signal area, I could still stop or dramatically slow down my data/phone signal by covering the phone's left corner too much with my hand. So while the bumper does help to minimize the left corner antenna problem, it by no means eliminates it. The flaw still exists, and a case does not truly render the problem unimportant. In lower signal locations, you will still see the phone losing it's proper 3G service if you hold it in certain ways.