I had forgotten about this gem but came across it on my hard drive an hour ago and wow! I remembered what a really wonderful sounding instrument that is.
User Interface: OK, as all mda plugins it's not supposed to be pretty, just work. It uses your host's interface with clearly labeled sliders that give exactly the tone variety you need. I think that approach works well, also the looks of the instrument never go in and out of fashion, it's sort of classic.
Sound: That's the best part. I've played with many epiano emulations (commercial and freeware) and this one is a great competitor. To be fair I'm not sure which of the instruments I've played is the best at faithfully emulating a piano, but regarding pure beauty of sound I think this one is a winner.
Features: This is a one trick pony so don't expect many features. It produces one sound, that is of an electric piano and that's it. It offers some extras like pan/tremolo, detune and overdrive which are more than enough.
Documentation: None, who needs it? It's very simple to use and actually nearly impossible to produce a bad sound.
Presets: Same as "Documentation" section applies here.
Customer Support: I guess it's extinct but I don't need it either. I'm just grateful that the developer gave to the community such a fine instrument.
Value For Money: Are you kidding? It's free!! As unbelievable as that may sound...
Stability: As a rock. Hasn't crashed any of my hosts.
As a conclusion this is one of the best instruments out there. It doesn't do a lot of things but if you need an electric piano you should grab it. These days I own the much hyped MrRay73 Mark II which of course truly deserves it's hype but the mda epiano is a really strong competitor if you also take into account that it's free.