Some great elements in here, doesn't always add up
First, some notes:
Pretty big bass sound there, digging echo/reverb. Not sure how well the sound works in an ambient song, though. Looking at it without considering genre, I'd say it was interesting- maybe fell a bit on the cheesy side with repeated listens.
Percussion is pretty trippy; interesting, neat stuff...I'm liking it. Composition, sound, I think you really nailed it.
Digging the background stuff, more often than not. Some cool sounds, not always sure if they fit. Enjoyed the throwaway string sounds more than the warm/soft pads, I think. I'm hearing some things the second/third/whatever time through I didn't hear the first time through, which is always good.
Crazy lead from about 1:20 on. Not especially liking it, melody wise or sound wise. Seems out of place.
Overall:
I like the structure, you certainly keep it varied and interesting. I'm never bored by the song, even with repeated listens. That's definitely a good thing. The song evolves, sounds bounce off each other, react. It feels organic, which is a tough thing to accomplish using sounds like these, I think.
With the soundscape, you are creating a lot of space. Feels pretty expansive, pretty mellow. Unfortunately this contributes to that one lead synth's and the bass sound's cheesiness, but that's opinion, of course. Also kinda makes it feel reserved, held back...not a strong sense of emotion. Again, opinion, some would probably disagree with me there.
Suggestions? Retool that bass sound, lead sound, really play around with those pads to make it all fit a little better. Maybe think about adding some stuff to compliment the great percussion, run with it...but that might lead it to not really be an ambient song, so keep that in mind. I think you've certainly got room for improvement, but it's still good as is. Sounds like work and thought went into it, so you deserve credit for what you have here.
Keep it up, drop me a PM if you work on this some more, update it, whatever...I'd be happy to take another listen if you do.