The most useful feature is that it allows you to search for specific data using key words or phrases without having all this information stored within each individual contact record (which would take up too much space).
It's not as easy at importing contacts into an existing system if you already have several different sources. I'm solving our need to track client interactions through multiple platforms but also keeping them informed about status changes/updates related to their account - so they know when we've been able to assist them!