it's true that this song is too short. :(
But if you think of it, some of Jay's fast songs are short. Sailor afraid of water is just 2:39 long, snake dance, ninja, goddess of race, all of them are less than 3 minutes.
About the 2 minutes preview, it was not official released, the songs were leaked. So the preview has nothing to do with Jay or JVR. And if you compare it to Twilight Chapter Seven, yes they both rap songs, but the tempo are slightly different, Twilight has really slow tempo even the rap part is slow, so of course it will be longer :)
Even if it's short, I still enjoy this song. Maybe if he add a bridge and then repeat the chorus one more time at the end, it will be better? Just my opinion.. :D