I didn't really get the "celtic" feel from this, but it is by no means a bad song, its still really pretty! I could totally see this being a forest theme in an rpg.
I really like this one. I fell in love with the percussion entrance at :16. I love the change at :33 too. I would suggest bringing out the stick clicks a little more to give that amazing celtic and barbaric feel to the song.
Please contact me if you would like to use this in a project. We can discuss the details.