You bet I would! Too many times, too many places, not only in restaurants, I've been annoyed or made privy to bits and pieces of peoples' private lives in which I have no interest, and in some cases, really did **not** need to know. This runs the gamut from arguments with the boyfriend, spouse, what have you, to whining pleading kids trying to coax a parent for permission to yes, "intimate details" being shared with a BFF over the phone! I mean really, folks, have some class! No one needs to know about your sex life while eating or shopping.
If there is an emergency, yes, take the call, but go outside. Otherwise, leave it on silent, and talk WITH the people you came with!
The Post Office now has 'no cell phone' signs up, and many banks also ask you to turn them off when you are at the window. It makes perfect sense to me. The proliferation of these devices, and the great numbers of people who seem to feel they cannot exist or breathe for a moment without the fool things glued to their ears are supremely annoying!