Summarising the good words by others...
(John Gruber, John Syracusa)
On the external antenna design:
"Overall the iPhone 4 performs better than prevous iPhones. Apple is very confident in the chosen design, BUT the design does make an antenna weak spot explicitly visible to the end users."
On the reception issues:
"Vast majority of users do not have reception issues with iPhone 4. The left-handed "death grip" way of holding the phone does cause problems for some, although this is not entirely unique problem to iPhone 4. While the weak spot makes demonstrating the problem trivial, it should not be confused with the experience of actual use of the phone."
"Actually in parallel, a real bug has been identified that probably is causing a part of the problems people attribute to the antenna. Fix for the proximity sensor bug is coming in upcoming software update."
On the free bumber:
"Apple cares about all users. We do think most people will not need a bumber solely because of the antenna design. However, we are willing to give one free to anyone who feels they need a bumber. We will continue to improve the hardware and software in the future products."
