"I'm a "Technic" guy and love to see how Lego replicates real-life objects with Lego bricks. I get all the hates about this set saying it's misleading. I do get it, yeah it's kind of misleading, but seriously, If you know anything about Lego, you would know it's impossible for it to be "playable" like a real piano at this scale and price. I like the way this set is, how it replicates all the important details of a real piano while offering some playability which the original design didn't.
Finally, I did find some issue about this set however, that the reset function didn't work so well to put the keys into their neutral position. The reason for this is that the technic beams that touches each other to stop the motor when rotating backward do not touch closely enough, plus the axle is too long that at the very end it's actually a little twisted. I've managed to somewhat improve it by adding a rubber band on the orange beam 2 to widen it just a little bit. But after you widen it, it will collide with the rubber axle connector so the "listen" function doesn't work very well, in order to fix that I replaced the rubber axle connector with the spare gold piece to fill the axle (don't know what it's called lol, see the attached pic for a better look). After all that changes, it's been working perfectly for me.
I think overall it's a beautiful set, the building experience is a little bit tedious due the nature of the object, but none the less an amazing set."