There's potential here. Build on that atmosphere!
You start out okay... that note progression is good, but could have been better. It's definitely something I'd hum. You give off a nice atmosphere with it - I'll go into that later.
Harmonies... that "da-da-da, da-da-da," thing is overused, though, and I think you could have found something better to use than that. The bass in the later bits of the song is too quiet and should be a bit more noticeable. The synth you introduce later on that plays a note every other beat (the first and third of the measure, I think) doesn't fit at all and generally makes the song worse. And ending with it was a bad idea, too... you could have had a good one with the synth you started with playing the melody. A mellow pad would have worked much better in my opinion.
It sounded like you didn't put any effort into your percussion in this song at all. You definitely could have tried harder... are those presets from FL? You could have tried to find a more realistic snare, which would have fit the idea of the song much more. Your closed hat doesn't work at all, and in my opinion could have used some reeverb. The kick I could barely hear.
Your choices in synths and drums didn't work at all. You could definitely have put more effort into that... it sounds like you did for the first bits of the song, but towards the end you took whatever you found that remotely suited your idea because you wanted to finish your song and move on. Again, drums didn't work at all, as I said and went in-depth about in the previous paragraph.
You could potentially have a very nice attitude to this song... I get a lonely, wandering-in-the-desert feeling from the melody, which is good. Should you have built on that with better harmonies, percussion, and synth/drum choice, it would have been a very good song... so next time, you know to start with an atmosphere and stick with it!
I hope all this advice helps you out in the future. Don't hesitate to PM me if you want me to review a specific song of yours, or if you just need a bit of advice on a certain subject. ;) Why don't you visit my audio page sometime at http://www.newgrounds.com/audio/view.php?id=1828837 and maybe leave a review for my latest, Lost in Time? Thanks, and I hope I've helped. =)