I think it's almost rude to assume "people are typically making it up" - just as it's rude to think everyone is having the problem.
I can only share my experience. I tend to have to get on very long Conference Calls troubleshooting for work. I had one of the original iPhones, 2G, and I never had a problem with calls dropping. It was a rock solid performer.
Now that I have 3G, I can tell you for certain, there is a difference with this phone - and it's my 2nd 3G (the first had a home button issue) and neither one has performed nearly as good as my original iPhone.
Just yesterday I was on a call in Houston with Great 3G Coverage - travelling the same freeways I used to be on with my original iPhone - dropped the call 3 times - then had "call failed" about a dozen times trying to get back on. At one point I dropped the call immediately walking in to a store. I thought, ok fine, I'll wait until I come back out - came back out and the phone showed "no service" until I turned on Airplane mode and turned it back off. So, I'm in the middle of a lagre metro area, standing outside and I have to manually get the phone back on a network?
This is just one example of many - there is a problem with the phones I have received - maybe not all of them, but certainly mine. And I'm not Making it UP.