Pesce is very good defensively, but doesn't provide much offensve. Some Canes fans feel he has untapped offensive potential, but I don't see it. Still, if he was on the Leafs, I could see him getting ~30+points just because he'd be playing with much better players and would get more chances to get assists. He's got an ok shot from the point, not bad, but not great either.
Defensively, he's very solid and does a good job at shot suppression. He's positionally sound, usually makes good decisions (when to pinch, taking the right angle, when to fall back, etc..) and is strong along the boards. He's a good skater, but to me, his stride is more choppy and not as fluid as guys like Slavin, or Rielly. He's a good passer and moves the puck well, but just ok handling the puck (you won't see him going around guys or end to end).
His contract is excellent for what he brings and can easily play against top competition. He's a very stabilizing presence.
IMO, I think it would be Pesce+ for Nylander, but many Canes fans disagree with that. Of course, that is contract dependent. If Nylander is going to get $8M a year, that lessens the value of him.