Tom H.
Yelp
Gets five stars because of the research and instrument samples, by country/region, for the entire planet. Yes, there's a rock representation, many guitars, but also many rare instruments, including very famous ones.
This is NOT like the Rock and Roll Hall of Fame in Cleveland. It's not totally complete, but excellent in representation. If you're an ethnomusicologist, there might be none finer on this planet. It is jaw dropping.
There seems like there is repetition, and there is, because many families of instruments are represented, and there are many members in families. Advanced modern percussion may be one of the few areas actually lacking, but it's a museum, and not necessarily a complete history of each instrument genre.
There are free headphones that link to each exhibit, and there are many many exhibits. These headphones sometimes don't link well to the specific exhibit, and this is my strongest criticism of the headphones-- their proximity to the exhibit isn't well-tuned.
But it's there. That timple you saw on Gran Canaria, or nine versions of a Qanun, or that shoulder-mounted e-flat trumpet. It's all there. There are a hundred+ versions of oud/uds. Lutes. Guitars. Guitar harps/harp guitars. Harmonicas. Pianos/harpsicords, clavinovas, Fender Rhodes, dozens of varieties of harps, more "brass" instruments than can be imagined. It is an unparalleled tour. There is a restaurant. The facility is beautiful and well-thought-through. Prepare to spend hours if you're a musician. Totally worth the rather high adult admission price (and no senior discounts). Musicians schedule concerts there; look online for details.
It's a superlative experience.