So far it seems the trade clearly favors WPG unless Roslovic will end up perpetual top 6 player. Laine has been all that WPG fans and those who followed his game knew him to be. Great shot, good passing, good stickhandling, good vision in the offensive zone. Weak in corners, cannot drive the play, can't really hang on to the puck in the offensive zone, problems with the speed of the NHL game, not-too-great defense.
In short: if he has time and space, he is very dangerous. Problem is, you don't get that often in the NHL. And since he cannot really generate any himself, he is reliant mostly on his line-mates to do great setups (not easy when the opponent is focusing also on Laine).
Despite getting the top line spot, none of the issues have been magically fixed. It is still early and possible that he gets a sudden boost to his game, but most likely the hindsight view of this trade will be trading a rather one-dimensional good scorer for a 1B center, which of course is in favor of CBJ by far.