Actually, I find the immediate feedback on mistakes (I see that Synthesia stopped moving) very beneficiary.
Also, not having a good memory, I see this strange chord, I figure it out, I try to remember it, next day, I need to figure it out again - it is so, so wonderful to immediately get feedback if I figured it out correctly.
Also, big advantage, I am more relaxed when figuring out difficult passages. No more worry I learn incorrectly.
ShiroKuro But if you want to improve your score-reading ability and improve at playing from a score, Synthesia will be counterproductive.
Personally, I think immediate feedback the moment I play an incorrect note, will help.
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... feeling like the pianist on the Titanic ...