He's playing alot better than I ever remember him in Dallas, although my assessment is probably outdated and a smaller sample size too.
What is an obvious upgrade over pateryn thus far is his ability to get pucks on net. He may not have that big shot that pateryn has but what's the point when pateryn has yet to prove that he can deliver it often enough, or even get it through traffic on a consistent basis.
On the defensive side, he's been reliable for the most part. There's not too many head scratching moments so far, and he is looking like a luxury as a 3rd pairing guy right now.
A seemingly low mistake rate and ability to get pucks on net has been Benn's stamp so far IMO.