The critical role is web URL filtering.
The GUI is quite nice.
The solution is not too expensive. It's affordable.
The solution does what it's meant to do.
The web content filter is the most valuable feature.
The solution offers very good self-authentication. It has a lot of protocols and ways to authenticate users by ID, or by Active Directory Integration. It's able to take credentials from the Active Directory Domain Controllers.
The ease of use. It's pretty easy to use and navigate the UI... to either block or whitelist a web address.