Not sure how good it is, or any system for that matter. Anything can be bypassed/shorted if someone really wants your car. It is just a deterent and nothing more. If I were to spend money on anything it would be more along the lines of recovery like GPS tracking/Lojack. What if your keys get stolen and then get used to take your car? Lot a good that high tech security with the really neat key fob does then. Even just a protected by Lojack sticker in the window is probably better than any aftermarket alarm. Maybe not really, but you get the point.
Thats what Ive been thinking, getting LOjack, but since the car is always in the garage I dont have to worry about it as much But I had my daily broken into at my house and they took everything even my school backpack that had books and notes in it.
Don't bother with the alarm ... if you keep it parked indoors that's the best you can do. Alarms are just deterents ... if someone really wants your car, they will get it. LoJacks don't stop the car from being stolen either ... just lets you know where its headed. Most times the perps want what is inside the car, not the car itself. Keep the interior clean, nothing out that is inviting to others.
I know the car can still be towed but there is no way anyone will be able to start it without the plug. I like the fact that it does not make any noise and there are no moving/electronic parts to fail. The car is really not exposed to any high theft areas, but it is $375 dollars worth of piece of mind.
If you want a GPS tracking system that doesn't cost as much as Lojack ($695 per their website), look towards SmartAlert, which is licensed by Ford and, if I recall correctly, cost about $345 when I purchased it. I don't need all the extra early warning alerts going to my cell and don't need monthly reports and all that other junk, but they are available if I upgrade to SmartAlert Advantage.