He's not much more than a JAG. He's being used as a rusher 1-2 times a game for an average of 2.8 YPC. I don't know if teams are going with a LB and the Pats are opting not to rush or if they're going with a DB and the Pats are opting not to rush. I do know that the Pats are predictable with White on the field. They're not running.
Of course, the Pats are pretty good at this stuff so they get him involved in the screen game to replace running out of the backfield and it's worked well against some teams. To his credit, whenever teams do gamble and put a LB out there White has done well as a receiver. So he is creating mismatches even if they are predictable.
But this is more about the Patriots taking advantage of what a guy does well -- be a pass catching RB -- and minimizing what he does poorly -- run the ball -- than it is White being a good player. All of Faulk, Vereen, Woodhead, and Lewis were much, MUCH, better out of the backfield. They certainly miss having a guy who disguises run/pass better than White as that's a big chunk of Gronk's value as well is keeping the Pats unpredictable.