The Clav-1 is a Clavinet simple sample player/vsti and it sounds quite good (for a clavinet). At least to me it sounds in fact better than the Ticky Clav VSTi which many people here seem to like a lot.
The user interface is nice and clear, maybe a better font could be used (to much vintage style for me).
All basic features are there, I do not miss anything. The modulation fx could be better but for that purpose many free vsts are avaiable so an improvement in this sector is not really required.
The presets are ok good/but but not too many. The docomentation is just one sheet, but more is not really needed.
Unlike the EP1 of Topaz (which I cannot get to work here) this thing just works fine. no crashes so far. thus I did not need customer support and so I cannot complain about it.
Since it's free: the value for money is great.(hey, but anyway, for a clavinet vsti I would probably never spend any money...)
give it a try! it's free and so there is not risk in trying it.