First: Ok the intro is OK, although it could've had a more obvious chord playing and the led can have more variations. But it isnt a bad intro.
Second: The buildup is very good, but you can add a rising effect and that will be perfect.
Third : The drop is a bit too loud compared to the other parts of the sound. A bass drop doesnt mean a loud drop. In most of the dubsteps, the drop has the same volume as the verses (although it appears to be not). Also you can use more growl variations to make it sound complex. The second drop is dope tho.
Fourth : The outro is too simple, maybe you can add a fading effect.