For some iPhone 4 users, the answer is yes, it is real and annoying. And no, they don't want to stick tape on it, hold it a certain way, or enclose it in a bumper case to fix the problem. Nor should they have to.
After having used one for 16 days now, I can happily report that I have no problems with attenuation at all, and I've used it in talking to people located near and far, and in various places on my end. I've paid no attention at all to how I hold the phone, and I trust I hold it as anyone would in making a call. My computer-savvy 5-year-old grandson has used it as a phone without any problems. At this point I can say the iPhone 4 is the greatest gadget I've ever owned or used, and I've worked with computers all my adult life.
From what I've read most people have no complaints about attenuation. The problem is significant for some users, though, and Apple should offer to fix it in some reasonable manner. The company has scheduled an iPhone 4 press conference tomorrow, Friday, July 17, 2010, and they will likely tell us how it plans to remedy the defective units.