I think the rule is, since he wasn't picked in the first round, he has to either be 22 or out of contract/released by his Liiga club if he is to play in the AHL. I don't know what his contract status is but he's obviously under contract for this season, as he's expected to spend the whole year with TPS.
He's a big, lanky kid who, if he fills out, should be a load to handle. Skates pretty well, moves the puck around nicely. I like him as a longshot prospect, but he is still really raw and needs a lot more time.