The Zyxel Unified Security Gateway solution is stable and does its job effectively. These are the main advantages I can confirm.

The most valuable features of the solution stem from web filtering, malware protection, and antivirus.

This is a capable appliance and the standard features work well for us.

The solution is good for freelance and routing, as we don't have a separate router.

It's usable for me, for my purposes. 

There are some filtering options such as peer-to-peer blocking and things like that.

The solution can scale well.

The cost is very low.