I have had one installed for several years. My primary problem was < 0.5 micron clay. I have never had a problem. Looking at input vs output water is impressive.
They do remove biologicals. It is not completely clear if they get rid of all viruses but I thought they have NSF approval for that use. The same materials are used in bigger systems (with some differences in the internal environment) to remove flocked particles used to remove other bad stuff. They do not appear to be damaged by chlorine.
They have an internal carbon filter. I have always felt that it is on the wrong side of the filter (input). I have one of those filters in now and just got the stainless steel mesh replacement. If I need carbon I will do it outside the Zenon filter.
This thing solves problems that other generally available home scale filters simply do not fix.
Nothing to screw around with. It just sits there and works. It does use some water for washing the filter.