I like that it allows me to target specific segments of my audience in order for them to get more information about our product or service.
It can be very time consuming depending on how many groups you are trying to send messages to at once. Sometimes it is difficult to determine which segment has been targeted so if they do not respond after multiple tries, then the best we could hope would be that maybe they were just busy doing something else. We have used this program to better understand who was interested in what topics within our organization.