Integration
Opening a compressed file just brings the Unarchiver pref window explaining how to set the app as the default one to open different format. This behaviour is useless.
You have to go through the file menu to unarchive the file. There is no integration in macOS (Sierra) at all. An action in the secondary click menu is very much necessary!
Gab.B. about
The Unarchiver, v3.11.1