I like that it's easy for me as an admin user, not having any technical knowledge is very helpful in keeping things organized! It also keeps us up-to date with our client information which makes life easier when we need help from them or have questions about their account/s etc..
The only thing i dislike at this time would be there isn't much customization but they are working hard towards adding more options so hopefully soon!! We've been using flexhost since 2008 without issue & haven't had many issues other than small updates (which usually fixes some minor problems).