I don't have one and don't know of anyone who does -- but in today's world, that's far from an indictment (given the sheer volume of innovations around).
I guess the only question I'd have is whether or not the system works if somebody winches the car up inside an enclosed trailer. My GPS units (I have 2) require a clear view of the sky and won't work inside any enclosure that provides much shielding.
What happens if the GPS part doesn't recieve when you "ping" it? Does it report the last position *known* or does it give an indication that it's not reading anything? I assume that it uses cell phone technology to communicate, so it's "reachable" anywhere a cell phone would work.
Overall it's a good concept, and it's certainly much better than nothing. No system is fool-proof, but those are a couple of questions that jump out at me looking at their website.
