It sorta sounds like a softned electric piano trapped in a set of tubes. But I like electric pianos in tubes. A little... um, hectic- kinda detracted. But good even so.
Up until the pan flute sounds entered, it was too complex. Simplify your music with some organum sounds (4ths 5ths and octaves only to make it sound smoother) and the subdivisions were out. It sounds good when notes are on off-beats, but not on every other quater-off beat.
Organum sucks. Leonin was a punk ass!