Tons of stuff going on in the background on this, because of this it sounds really fleshed out. The melodies are really good and there's some awesome composition and varieties/fillers. I really like what you did around the 2:30-50 mark, really neat melody. The pads in the background are awesome and add to the atmosphere perfectly.
This is definitely one of the best songs I've heard from you and some of the best mixing I've heard on Newgrounds.