In Ocarina of Time and Majora's mask, you had to remember (or look up) songs to play on the ocarina. In Skyward Sword, Link's instrument was the Goddess's harp. How do you play it? Oh you just swing your arm back and forth with the wiimote... Zelda would be so proud!
P.S. The harp is actually a lyre, and the tones produced by it will follow the harmonics of the background music in the location it's played (according to zeldawiki).
Which instrument did you like better?