Pros
Alarm.com is an incredibly social and fun place to work. Your co-workers tend to become really great friends that you enjoy hanging out with outside of the office. Inside the office it's a work-hard play-hard kind of atmosphere. There are plenty of opportunities to work on cool and challenging projects. The benefits are really good and depending on your manager, it can be a personally rewarding/but rarely financially rewarding place to work.
Cons
Alarm.com typically pays below the market standards by a minimum of 10% and a maximum of 30%. Very slow career growth opportunities and promotions and added responsibilities are not usually met with added pay. I like to think the freedom of Alarm.com allows employees to work on cool projects which are good experience and good for your resume but after a while you've done your time and it's probably good to move on and leverage your new skills somewhere else. You could come in and work extremely hard, or come in and work very little, and it's likely no one would know the difference as long as you take care of your core responsibilities.