This is wonderful. I really like all the ambient I've heard from you and this is no exception. Echoing ms's praise, the samples are all very crisp and nicely balanced. I never felt like anything was overwhelming other elements without it being purposeful.
So, criticisms, keeping in mind that they're little bitty things that you may or may not want to address:
There's a moment around the :30 mark where the background sample (leaves?) sounds like you're violently opening a bag of potato chips. I couldn't get the image out of my head.
Ambient or not, it gets a little slow around 2/3s of the way in. I could do with a bit of a bang or change up, even just momentarily, to break things up. Go throw a rock in a dumpster or something.
I really like the repetition of the low drone rising and falling throughout the piece. It reminds me of a sleeping creature's breathing. My issue would be with the sort of whooshing phaser rise and fall that's almost wind like and comes in later - it just gets a bit repetitive in the second half of the song. A little variation in tone wouldn't go amiss with me there.
I like the main synths being straight up the middle and the field samples being in stereo but I'd like to here some separation on a few of the one-off elements. Not enough that they squash the samples but enough to give it more of a sense of space.
Again, minor little things and really just personal preference. Technically it's spot on and it's a great listen that I'm sure I'll come back to. I'd love an album of similar stuff.