I caught 2 Swiss games, the WJC games, and a lot of the WC games.
I actually think his game grew a lot even in the time between the WJC and the WC games.
He skates great, his shot is lethal, great hand eye, an impressive 200 foot game, and at games in the WC (not WJC) - Ray Ferraro described it best, "one man cycle" couldn't get the puck off him and he's damned study on his skates.
Toews/Kopitar but with a better shot is the play style I would describe with obvious refinements to come to his defensive game, but that'll be with experience.
Marner is electric, so is Nylander but just wish he was hungrier to go in and get the puck, but have to acknowledge he's equally as crafty and dangerous with the puck on his stick as both Matthews and Marner.