First dubstep? This is a really good start. Loving it. Those drum samples are surprisingly full. Nice work with them. A few things for your next outing...
1) Motif. There really wasn't one. The track started out on a bassline and it just maintained the same energy level through out. A pad could really help add some atmosphere to your music. Be it a string orchestra, a soft saw wave, a synth chorus. The possibilities for pads are limitless. They add character and depth to a track. Without those few background noises you added this track is predominantly just two instruments. Add some more textures! Drop a few more voices in there :)
2) Rhythmic variety. That beat got a little stale after a while. Drop some drum hits in new places, add a fill at the end of a measure, add some tambs or some toms. You kind of changed the beat at 00:42 but then it went right back to that hip hop beat. "New" beats don't have to be vastly different. Just, add a kick or two to the "old" beat and it will really add some dynamic changes you may not have been expecting.
I saw your thread in the audio forum. I'm not aiming to hurt feelings when I leave reviews like this. I really just want to see people improve and get better. I've seen so many artists come and go over the years but it's always fun to notice the progression that happens to the ones that stick to it as time passes. Keep on keeping on, you have some serious potential! Loving it :)