I disliked it, but I also hated all of the melodies - to me the harp just didn't sound realistic (too fast, too computer generated). Plus Fi singing and the dragons, blah. (loved the regular musuc though, just not SS's melodies you needed to perform).
The worst instrument to play however had to be Spirit Track's panflute. Trying to blow into the mic, my face up to the screen, going cros eyed to make sure I was blowing into the correct color with the stylus was horrible. At least the harp wasn't difficult to play, though maybe that is part of the issue with it. You really didn't need to care about any of the sounds to play that instrument and it fact (referring to the lumpy pumpkin part) turning to tv to mute seemed to make it easier to complete.