I have absolutely no problems making a call when there are no bars showing.
I agree. My DINC2 (my first Android, just switched from BlackBerry last week) always shows fewer bars or reception than my Tour did, but I have had no problems with actually placing a call, and I've noticed a few times that it has shown no bars.
The only problem I've had at all is when I talk to my wife on her new Fascinate, there are times when there is a lot of background noise. We each hear the same noise, and it makes it difficult for us to hear the other person. Neither of us has experienced this issue when talking to anyone else, and it doesn't happen all the time, so I'm still trying to figure out if the problem is my phone, hers, or something entirely different. Very weird. But the actual call reception on the DINC2 has been excellent everywhere I've used it thus far.