My experience is totally opposite. I've been actively using mobile phones since 1995 (I'm in the industry) and I've extensively tested probably hundreds of them (software&service development, network testing etc). The IS is one of the worst I've ever used in regards to 2G/3G radio sensitivity. My oldest Nokia is still far superior in comparison.
The antenna design in this phone is abysmal. I do hope HTC manages to develop a firmware update that improves the reception. I hate the lousy reception but I love everything else about the phone. Oh well, the camera could be better (less compression and less over-aggressive sharpening, please).