I don't know Steve. That can be hard to establish. Are we speaking of Arturo the DM or Arturo the CM? And even then, is he a box to box or what?
As a DM, he's great. He's got a very energetic style and is stuck to the opposing player like glue. That's one of the most annoying things you can have happen to you. One small error or turn and Arturo is there to snatch the ball away. His tackling is also great, just flawless, can't describe how good he is at that. As a DM playing the role of a destroyer he is quite good.
Then comes the running. He basically never stops. You can see him all over the field, and what is more important is that he can contribute all over the field also. So as a box to box mid, he's also quite great. Saving goals and throwing his body in front of balls in our box and then providing assists and scoring in the opposite box.
Great long range shooting. He's shown it before but lately doesn't show it as often. I think it's a team philosophy applied by Conte to keep possession and get as close to the goal as we can before we score. Can't say I'm crazy about it as it's what made Arsenal notorious for "walking it in". But in case we need that extra long range factor, Arturo is there to contribute.
His passing isn't great by any means but it's effective. Can lose the ball quite a bit at times, but not in a way that hinders his contribution. I'd say he's the best at what he does in Italy. EPL has Yaya, De Jong, and a couple more. La Liga has players like Mascherano, Alonso, Biscuits and so on. But they're different from Vidal and offer different attributes to their teams. Our Arturo is one of a kind and has the potential to take the world by storm as he can be a lot more complete than the rest of his fellow colleagues.