Whatever is important to you. Main point is probably if the
keys 'feel' good (and all are working etc.). Experiment with
the shape and velocity settings to see which works best with
your software. Test the mod wheels and the pedal inputs.
As a midi controller the Fatar is very primitive, it's
main quality (for me) was the 'feel' of the keys. I use
it mainly to play piano (also organ, but that feels some-
what strange).