The VirtualCZ rates high among the software synths I really regret that I bought. I understand that it is a sonically accurate emulation of the original h/w and so, I guess that my disappointment should be equally directed at Casio.
I find the sound more dated and wimpy than virtually any softsynth that I own (a license for). The envelopes appear so soft that it seems virtually (!) impossible to get any 'snap' out of the VCZ and ballsy it's certainly not. I wonder what kind of music people use it for? Chorused pads?
For myself, I find that I need a whole chain of fx after the VCZ in order to mangle the basic sound into anything remotely interesting, although the lack of snap is difficult to compensate for. Comparing it with a roughly contemporary synth, the DX7, is like night and day – the old Yama is certainly snappy where I find the Casio spongy and soft.
Obviously not my sort of machine, but hey! – who am I to discuss taste? No doubt the VCZ serves the musical interests of a number of people – it's just that I can't quite identify myself with those interests.
It's been a while now and there's also has been a few expansions that sound great but you REALLY NEED TO FIX THE browser now. It's a disaster. There are different kinds of sounds all over the place and I can't tag them. PLEASE.