We just recently like within the last 6 months got a security system with Vivint.
I think it is worth it. I have been happy with them. They installed everything and gave us all the gear for nothing...we signed a two year contract. All doors and windows have sensors, they also gave us a case of energy saving light bulbs, the electronic control panel, a camera, the automatic door lock thingy, and an electronic thermostat. We have an app on our I-phones to access the control panel, door locks and thermostat from out phones. We can also view the camera footage from our phones and control the movement of our camera from any computer or the app on our phone. Anytime a window opens or door a text is sent to my phone...so I will know if my kids try to sneak out and night or anything. If I turn off the heat while we are gone I can turn it back on before we come home so the house is warm when we get here.....It is AWESOME!
Of course we also have a Yellow lab and a big English Mastiff.....so those don't hurt either!