I saw Canada the most, so I'll do them first:
Studs:
Staal, Toews and Downie were by far the best players on the team
Price played well, though he looked shaky in this game, he still made two HUGE saves (though I felt the 2nd goal was weak)
Letang
Parent
Russell (I can't believe how good this D corps was)
Helm - doesn't lose a single footrace, and makes good strong plays, very very impressed by him
Pyatt was real good as well
Duds:
Cogliano looks dangerous, but didn't supply as much offense as i expected
Marchand - liability on the first line IMO, I was surprised they never took him off it (though he did score a good goal today)
Gagner - I understand that he's 17 and will be better next year, but he just didn't show much at all.
Other teams that I saw:
Studs:
Omark
Backstrom - people say they were disappointed, but he was good when he was on the ice, just wasn't on the ice enough
the Johnsons, both were great in the semi-final after a poor showing against Canada in the round-robin
Kane
Hjalmarsson
Chorney - this guy, IMO, will have the best career among the American defencemen after the Johnsons. A really good choice for captain if you go by his on-ice play
Surprisingly (to me), the Russian D corps, with Buravchikov, Zubarev, Anikeenko and Valentenko, those guys were real good.
Duds:
Bergfors - this guy's in the AHL?
was disappointed in Cherepanov in the final, since so much was said about him
Okposo - everyone said how good he had been, I didn't see any of it, wasn't very good for a guy who is supposed to put the puck in the net
Brian Lee - so far, not justifying being picked 9th overall
that is all so far