The hardest temple for me was the Water Temple from Ocarina of Time. I would get lost multiple times and find myself back tracking on several different occasions. Raising the water levels was a bit of a hassle and I had trouble getting to where some of them were, I guess if I had the scarecrows...
An instrument in which you use your mouth seems a lot more intimate and personal to me (this is not intended to be a dirty representation of the instrument).