I used ADT for two years in Chicago and had no issues with them. I switched my service here when we moved to Bucks County. Unfortunately, ADT did not show up for the install--despite several phone calls assuring me they were ""on their way"". I waited for five hours. Believe it or not, I called again to reschedule the install, and they didn't show up again! The technician called me several times during my second five-hour wait to tell me that he would arrive soon. This is not the kind of service you want from a security company...or any company for that matter.
Pros: My insurance company recommends them.
Cons: They do not show up--unreliable!