This is nice; I definitely see the elements of a great tune in progress here. But in its current state, I don't think your song manages to reach its full potential. There's just so little variation overall to justify the five-minute-and-a-half duration, and it feels somewhat unfinished and even rushed at times.

The dubstep aspect is a great compliment to the ethereal foundation that's been built, but perhaps differentiating them in each segment you've laid them in could have resulted some well-required diversity. This is something I feel a lot of material in this genre overlooks, and when there’s no vocals around to distract you, it becomes very apparent how repetitive electronic music can be. It’s very subjective whenever or not songs can get away with this, so I’m not deducting any points for this in particular.

Ultimately, this begs for a more proper (and satisfying) finale; I'm not going to pretend that I know the best solution to conclude your efforts with, but because the song never prepares you for an ending, it stops rather abruptly. Maybe if you kept the drums playing without fading them out as fast as the other timeline tracks, it could have sold the effect better? Again, I'm not a music producer, so this is just a mere suggestion.

Speaking of the drums; I know it's been noted in the reviews prior to mine, but they sound too vicious and loud. It feels like they're competing with the synths in order to maintain the primary focus of the listener's attention, and it establishes a busy environment as a result. Now this can work depending on how fast the rest of your song is paced, but as you've decided to do a more sustained composure, it really doesn't work in this situation. The rhythm is good; just exchange them for some softer samples next time.

Since you've released this around three years ago, I highly doubt that this song reflects on your producing skills today. So I can only give you an opinion based on a retrospective, and for what it is, this is still a very good piece of history. I'd love to see you re-attempt this sort of material in the near future, and to hear how much you've improved.

Good effort - keep it up.