I have kept Onstar on my vehicle for 5 years. It found a safety issue (not a recall or a GM issue) with my vehicle, notified my dealer and emailed me that there was a problem. I have had to push the blue button 2 times. 1 time for a medical emergency, the other time I was stuck in a horrific traffic jam on the interstate, there was no cell service because the semi trucks were blocking the signal and my car was sucking fumes. They patched through a phone call for me so I could make arrangements to have gas brought to me from the other side of the interstate.
My husband refuses to discuss canceling it because I have had to use it.
Yeah - it can seem like Big Brother. I don't feel it is any better or worse in that respect, to a cell phone that tracks your movements even if the phone has no GPS on it.