http://www.anandtech.com/show/3821/ipho ... signal-fixYou have to remember the majority of the issues are coming out of the US. ALL iPhone 4's are on AT&T. AT&T's network compared to ours is shite! Peoples bestcoverage over there is 2-3 bars, not the 4 or 5 we get here. Also the test's done by anandtech show you can have a call and have full data with only 1 bar of 3G coverage.
The phone itself delivers better battery life than anything else in its class, has good performance and a wonderful screen. Whether or not the antenna design manifests itself as an issue really depends on AT&T’s coverage where you’re using the phone. As a result, AT&T can also share in the blame here.
The above article is indepth, but here is part of the summary. With a bumper the phone behaves as good, if not better, that the old iPhone!
Criticism that isn't constructive is rarely useful, and as we’ve just shown there are things that Apple can do to address the issue today. Using a bumper the iPhone 4 behaves no differently than the 3GS. Hold the phone as tightly as you want with a bumper and it’ll lose as much signal as a 3GS or Nexus One. Put some sort of insulating coating on the stainless steel band and you’ll significantly reduce, but not eliminate the issue.
Why wouldn't you have a case or bumper to protect a $1000 phone like the iphone?