Pretty ok, I might use it in a level.
Um ok, first of all, a dubstep track is never shorter than 2min, and the tempo is a lot faster then 140 bpm. The rhythm is good, very bouncy and hype, but the melody is detuned and too simple, no changes in the notes. If this had a slower tempo, longer and the melody is more complex, it would be a lot better. But don't worry, I know that it is your first submission and you will improve from now on!