I have it, and your assessment is accurate. It's cool to a point in that you can look online and see where your car is, but I'm not exactly sure how valuable that is. Probably not $750 valuable.
You get x number of "free looks" (15?) but then you'll be charged a nominal fee for looks. I used one, just to make sure it worked but haven't had a need to log on since.
I'd consider it only if you were a believer in LoJack type systems. I bought it in a moment of weakness, but actually think if someone stole the car, I'm not sure I'd want it back. Somewhat surprising is that it's installed on the box, but not on the mercedes which is probably more likely to be stolen.
From that same "popular" dealer you can get Permaplate treatment, which is something I actually think has been worth the money...more or less
