Quite interesting.
Some transitions between things would be nice, the fade out fade in in 0:38 was quite weird, just like the ones in 3:47 & 3:55.
The melodies could change more too, the lead stuff you have first time in 0:13 is awesome, but you could change it a bit every now and then.
Also, it doesn't feel like this song is going anywhere, it's just standing there and trying these few things. Not a bad piece at all tho (: Just needs some variation and better buildups/transitions.