I'll offer my honest opinions: Sounds amazing! The lower/louder drumbeat seems to be a bit too "close" sounding or something, particularly at the beginning. It could stand to be a bit more mellow and quieter, I think. The melody is simple and nice and varied some. The atmosphere is gentle but very active. I get the feeling of a jungle cavern lake brimming with life. Or perhaps a moonlit forest; Grin.
Oh the piano at 3:00! Sweet! But then it sneaks out of the scene. The transition thingy at 3:40 is too loud and it quickly dies back into the old stuff, making for a rather awkward effect. But the old stuff is great and the return of the piano is very cool. I think the first piano section would sound better fading directly into the awkward loud transition instead of having the dead section between.
I can feel 10 hours of work in this. This, to me, is one of those oh-so-rare not-boring ambient tracks. :)