It's not worth posting in that thread anymore. Nobody is reading what is there, and all people are doing is arguing. That type of thing always happens when a handful of people DO experience real problems (antennas can go bad on any phone, not just the iPhone and arrive somewhat DOA) and then not listening to people who offer help.
3G IS spotty in some areas (it's only available in less than 20 percent of the USA)
The new cases DO cover up the antenna, which causes problems. The new antenna is in the circle around the camera opening, and in the metal bezal that goes around the rim of the phone. If you completely cover that with a cover, and then your hand on top of that, the reception is going to be poor no matter how strong your 3G signal is. People have been arguing that and ignoring the people who confirm that taking their cases off actually resolves their reception problems. That can go on for dozens of threads until someone changes the topic.
3G in the US can drop out from block to block, neighborhood to neighborhood, even where ATT indicates that it is "best coverage". Their maps on their website are completely innacurate and have not been accurate throughout the 3G rollout the last three years.
And worst offenders: people clearly indicate that there might be something wrong with THEIR iPhone (not the worlds iPhones) and tell them to take it to Apple for repair or exchange, and that sets off a bewildering furor in the original complainer. Sometimes things just are what they are, or don't work and need repair. Arguing about it for dozens of threads is going to do nothing to resolve that stubbornness.
Welcome to the forum -- but take some of what you read with a grain of salt.