On the Forecheck, SB Nation's Nashville Predators blog, has an exclusive interview with Chief Amateur Scout Jeff Kealty. It's a good read in preparation for the upcoming NHL Draft.
I especially liked this part as I've wondered these things myself.
Q: How do you go about comparing prospects in North America vs. Europe, considering the fact that a kid in Canadian junior is likely playing a major role in a league stocked with his peers, while a young player in the Swedish Elite League is playing against grown men, and may only get limited ice time?
A: Every kid, no matter where he's playing, is a bit different. You have major junior in Canada, you have kids playing in Europe, you have high school and college in the U.S., so you have all different levels of play and avenues that players can come from. One thing that we try to focus on is just watching the intangibles with players, because sometimes no matter what league you play in, those intangibles (like hockey sense, work ethic, and character) are what can elevate a player's game from one level to the next.