Have you ever tried Carshield?

I keep seeing adverts & receiving snail mail adverts for joining Carshield. My last mechanic always told me that they were a ripoff. He recently retired & now I’m wondering IF they really are a ripoff or IF maybe he just didn’t want to deal with them. I’ve never known anyone who signed up with them & I’m looking for someone with personal experience. Nothing I’ve seen gave any indication of how much they charge for their services & I don’t want to contact them & get on their calling list!!! So, have you tried Carshield; & IF so, what was your experience???