Pros
You get what you put into this job. Best piece of advice is to find out who the successful sales people are...you'll know them because the sales numbers are public knowledge in the office. Buy them lunch and shadow them to learn what they do so that you can imitate their behavior. There is serious money to be made in alarm sales. A six figure annual income is a very real possibility. You just have to put in the time and attach yourself to the smart people in the room on the sales and on the installation side.
Cons
Be prepared for lots of training, lots of meetings, and lots of phone calls. The pressure is on to hit sales numbers, but if you are eager to learn and seek out help...showing that you care about your job...they won't run you out of the office over night. Be ready to repeat training and practice activities if your numbers are sub-par. Also watch out for incompetent installation people. Many are great, but the awful ones will literally cost you money.