I don't know what your definition of "special" is, but I think he's a good player. He's pretty technical (good shot/passing/crossing/dribbling etc), decent pace too, and he can do a job in a few positions.
Usually plays in Sensi's position as the LCM in a 352 but has also played as a right winger, left mid, AM and even a forward. To me though, he just seems like an attack-minded midfielder who is relatively comfortable drifting wide and back centrally.
Look at that 90th minute chance Sensi had against Dortmund - he passed vertically to Lautaro who held off his man and laid it off for Politano who laid it off for Sensi to work into space and shoot. Nice vertical passing, nice movement, nice give-and-go stuff through the center.
I feel like in Sensi's absence we've seen a complete inability to attack in this fashion. None of our other midfielders like to really get in between the lines and run at defences. Our other midfielders aren't really built to play in these tight spaces. De Paul could, to a degree, help in this regard. (As could someone like Vidal or Rakitic for that matter)
We won most of the games in Sensi's absence so it's hard to complain, but I daresay a midfield trio of De Paul - Brozovic - Barella is much better than Barella - Brozovic - Vecino/Gagliardini.
At 25, he's not young but not old by any means either. Perfect age. I am 100% in support of signing him if we can get him in on a similar deal to Sensi, say a loan for a small fee or player swap, plus option of ~€25m.
We've bought a lot of "promising" AKA mediocre players at that price point. It's subjective, but I think De Paul has the quality to succeed where the likes of Gagliardini, Vecino, Dalbert, have been inconsistent or underwhelming. He might not be that direct injection of game-winning influence, like Vidal (in theory) but he'd be a good signing IMO.