I don't really know what's a good score. (I guess if the middle circle is smiling? I somehow completely didn't notice that the first time I played.) Looks like my first time I got 102, then 40, then 120, then 477 (I was trying to lose that time to see how high a score I'd get), then 144. I'd consider myself at least fairly goodish at understanding RGB.
It sometimes feels like the colors change more suddenly than I expect (though maybe that's just how RGB works), and that maybe the color sometimes lags behind the sliders or something, though I'm not sure if I'm just imagining it.