Yes, but I don't count on it to keep us safe. In fact, I don't turn it on at night because you can't hear anything when it goes off. Forget being able to locate the sound of glass breaking or someone walking. Instead, we use the alarm primarily for three things:
1. There's a perimeter chime that sounds whenever a door or window is opened. That makes me sure that nobody can sneak in without us knowing while we're there. No kids sneaking out, either.
2. The smoke and fire alarms are integrated into the system, and the monitoring company will call the fire department for us if we're out. A few minutes might make a big difference with a fire.
3. When you come home and disarm the system, it will tell you if there have been any problems or if the perimeter has been breached. That way I know there's nobody waiting in the hall closet to smack me with a sock full of pennies.