I liked that it could be used with Facebook ads, as well as other ad networks like Google or Bing etc., which is important to me since we use both platforms for marketing our own sites/businesses at The Bookmark (and also in many cases just advertising each others' products). We didn't realize this before when using their service but if there's another person who can help us set up campaigns then great - otherwise they're very helpful from what my experience has been so far.- not having more than 1 page view per day counted towards campaign goals- sometimes difficult determining how much time was spent viewing specific pages vs clicking around within them.