I just watched the video of Finland-Sweden in at the 5-Nations tournament in Czech Republic (happened a couple of weeks ago). Here's some things I noted about Nattinen. Keep in mind I'm just a fan, and I was only watching him for the first time.
He was very relaxed. He did everything in a relaxed manner- taking face-offs, carrying the puck, backchecking, playmaking. However, he never seemed to be out of position. He was always supporting the play by staying near the puck, so it was hard to tell if his relaxed manner represents a lack of intensity, or if he is just a cerebral positional player who waits and watches for his opportunity. The coaches used him as a first line centre and on the point on the first PP unit. Got off one good shot on net that I saw. Showed decent puck handling, passing, and vision, although he didn't show them often. He carried himself like a talented player, but I had a subjective feeling that he could have done more if initiated the play more often. Still, even one viewing was enough to see he has a tempting combination of size and skill.
I should note that he got 6 points in 4 games in this tournament. No points in this game though.