Listened to the above link and watched more highlights... I'm really excited about this guy. He's my official favorite pick of the draft (though I generally know nothing of college players hah). He displays good vision, from what I can tell... has patience, and turns on the burners at the right time. Isn't afraid of contact. Will get low to meet 2nd level players to push through them. Makes clean cuts, but doesn't dance around and run backwards it seems. But again, this is just from highlights... for all I know, the non highlights he's screwing the pooch every play. I think his power running style will work with Roman's designs quite nicely. Since I don't have any attachment to Brown, I kinda hope Williams makes the team instead of Brown if they only have room for 3 RBs.
Edit: Found game clips... the above stands... he sometimes gets tackled a bit too easy in the legs because of his height, but that's just the downside of his size. Also, I notice a lot of defenders take bad angles on him... I assume, partially, because it's college ball, but I also wonder if it's because he has deceptive speed.
Also, then there's highlights of his defensive/special teams: