I love that you can upload your own photos or use stock images for free! You also have access from any computer which is great if someone loses their phone/laptop but has internet (which happens often in my office).
It's very easy once set up because there are so many options it makes setting all this stuff together super simple - especially when compared against other services like Adobe Creative Cloud where each product requires its'own license key & setup process!! If they could streamline those processes just slightly then we would really be able solve some problems our clients face daily regarding creative workflow management.