Every prospect has some things to work on, but I don't think you described constitutes as raw or is a big enough worry, considering his role on a team.
What he does better than every prospect except Dahlin is defend. His positioning is excellent, he is very hard to beat 1v1, he clears the crease, he wins puck battles, he blocks shots, and he is a decent skater and puck mover. There are guys in this draft who's calling card is skating and moving the puck who don't even do it that much better than Samuelsson who some people will like more than Samuelsson just because their calling card is puck moving, even if their overall contribution isn't better than Samuelsson. Samuelsson being a defensive defensemen will have some actively dislike him because of that, and think he's a plug.