I have one, I think I've maybe used it once. It just sits on my desk at home, I never take it with me anywhere.
I just don't use the phone while driving. I figure if I can't answer it, and it's important enough, they'll leave a voicemail. IMO, driving with a headset is just as dangerous since you're not giving your full attention to the road. Besides, a bluetooth headset would make me look like a tool, and I drive a stick and can't hold a phone, so talking and driving is out of the question anyways 😀