The ease of setting up an account, how quickly they respond to emails (sometimes it takes days), that I can control who has access to my information when i'm away from home via phone or internet connection.
Nothing really - other than their customer service could be better! Don't use unless you are dedicated enough with your time management skills as well. It's easy for me not having any kids at work yet so this helps alot since we're able to set our email addresses without needing anyone else involved like children etc..