He's from the WHL, I never watch that league.
He's tall at 198cm (6'5)... so thats a plus. Dunno how he'll be against bigger/stronger opponents. The average height in the NHL is 6'2. He was scoring a point per game in WHL but its not like he was tearing the league on fire considering he is 87th in league scoring. On point per game basis is 47th.
But like I said, I don't watch the league so I don't know what to expect from him. Seeing scoring highlights is one thing (shows what he can do offensively) but you have to watch a couple games to asses how he is overall.
My guess is he was taken most for his size rather than his skill. Haven't seen Rasmussen play so can't say for certain. Last season Stanley from Windsor Spitfires was chosen in the first round for his size. Difference with Stanley is guys who are in the 5' range push him around and he is crap defensively for the OHL level. I've seen/heard Stanley get yelled at by Spitfire fans during home games. Guess the hope is he puts on tons of muscle and can actually use his size but he plays more like Ericsson. Big body who dosen't use his size, has no shot, passing ability is limited, and defensively isn't great.
http://www.eliteprospects.com/player.php?player=240108