We just signed up with Vivint and had a security system installed at the house. The tech that installed our system, Frank, was on time (even early!), friendly and very considerate - offering to clean up everything and making sure that every was set correctly prior to leaving. We requested some placements for our sensors that were, I guess, kind of out of the ordinary - but he was more than happy to help us out saying "it's your system, we want you to be happy with it". Great customer service attitude.
One of the coolest things about the system is that we can control our system remotely - either over the web or via smartphone app. If you feel like you forgot to arm the system when leaving - you can check the system's status from anywhere! (And turn it on remotely if you DID forget). Super duper!
The salesman that we placed the order with on the phone was good - but neglected to tell us that the contract period was 42 months(!) until the end of the call. Looks like we're going to be secure for a long, long time.