Not too bad.
I like the effect at :09, and I like the drums throughout. Most songs (ambient especially) will have a melody that last for maybe a measure or two, then they'll change that melody a little in the next measure (or two), and then go back to the original melody, rinse and repeat (though you can add another altered melody in there if you want). Your problem (in my opinion) is that you wrote such a long melody that it sounds a little random and strange. Keep it up though!
Overall, 8/10, 4/5.