First impression: Interesting tune with the main synth in the beginning. When the harmonics come in, it's very nice. At 0:50, I noticed the tune had changed. I didn't even notice the shift... Nice work there. Only at 1:36 did it really change though.
Second impression: It's peaceful. I don't see a tune at 1:36 onward though, it's all really harmonics. At 2:25, it goes back to the original theme. At 2:45, I think the single note goes on for a /bit/ too long. The tunes could use some changing at this point...
Third impression: 3:11. I've heard this before! Still mainly harmonics. I kind of skipped through the song at this point before actually listening to it fully, and heard no real changes, so... can't review that much more. lol. The outro is just a fadeout, which I suppose works, but... a tad "meh".
Overall impression: This seems to follow an overall ABABA format, though there could be a bit more variation, so I have less complaints about formatting than I would. I am content with the overall formatting. Now to get more nitpicky. The tunes don't change, and there's not that much to keep me interested past the 2:30 line. This would work for great background music in, say, a game. But not that good as a standalone piece. The mixing is good. What I have to say, is have more tunes, more keys, more changes in rhythm, variances in melody... spice it up a bit and make people listen, don't have them listen simply for the sake of having background music! If you can succeed at having it be background or good for focusing on, then that shows a really good bit of music.
Hope this helps you.
-Review Request Club-