Yesterday, I went to lunch with a dozen or so Apple enthusiasts, all of us with our new iPhone 4's. And, yes, the topic of conversation was (as you would expect) the awfulness of the signal issues. There were various bumpers and other cases at the table, along with empirical testing. It was very clear that while the bumper added some protection against signal degradation in weak signal areas, the iPhone 4 would not perform well when held with the left-hand kung-fu grip of doom, even with the bumper.
With earlier models of the iPhone, it was easy to switch service from one phone to another. Starting with the 3G, you could pop in any AT&T SIM and expect it to work. But the iPhone 4 changed the rules. Its smaller form-factor MicroSIM doesn't fit earlier models, making it more difficult to move your service.
Enter the Micro-SIM adapter. Sold by the MicroSIM Shop, the €5.99 adapter (it is sold from Vienna, Austria) allows you to pop your iPhone 4 or iPad 3G SIM into a plastic shell that lets you use it in the iPhone 3G and iPhone 3GS. It works in the first generation iPhone as well, but requires a jailbreak hacktivation to use the SIM without activating through iTunes. You can also pop that same SIM into many other AT&T phones or into an unlocked third party phone.
Read on for more of TUAW's review.