You said it
I think you said it, it's your first take, it shows, but it isn't at all bad. I feel the dubstep elements were short lived, and when they hit, they weren't as solid as they could have been. The good part is, you did an interesting turn around. I was listening and thinking 'this isn't no darn dubstep' then you flipped it and did a good job of not sounding like two songs just thrown together. Keep it up.
Other thoughts; pay attention to your LFO sound, make sure it has a sense of pitch. You got the LFO part right, but the bass itself didn't really have enough pitch presence. I know some dubstep does this, so this may just be personal preference.