As an hiring manager I have used Offerzen over the last two years and have successfully placed four team members of my current team. I even got placed through the platform myself, and I recall it was very easy to get onboarded, and as a candidate the support was great.
It's a consistent interface and makes it easy to review skills and CV's to drill down on the key aspects of the skills I am looking for. Getting the ability to see the relative popularity gives you an added impetus to know that you need to get a move on . The search and filtering features are powerful, once you get to understand how to use it well. I do find it easy to use and use it weekly to review new candidates, if I have current open roles.
The interaction via the messaging is usefull as well although the majority of the communcations post introduction happens off the site.
Recently we had some challenges in finding the right candidates, and they were very helpful in showing us different ways to retrieve the profiles we were not seeing.