It's got a great beat, and you totally had me jamming to the rhythm. I can imagine this with some interesting variations on those string harmonies; not to say that I don't totally dig it as is, and I've never really been that into the Hip Hop genre, so...well done! The brief interlude of sparseness near the middle is pretty cool; it's one of the few times when you can really hear that sweet bass line. I'd be curious to see (hear?) what kind of lyrics you would come up to go along with this.
I was kind of hoping for a little more variety in the harmony progressions. The combination of brass and strings just work so well together...