I have to say that Magnússon scares me too on occasions.
No, he’s not crap - far from it, and he is definitely improving all the time. I just still feel scared when he is under pressure from an opposition player near the edge of our box in a fast-flowing situation - more so than the others. His distribution has been poor on occasions (not always, and as I said he is improving) and I’m terrified he will give the ball away in a dangerous position.
Having said all that I can’t think of anyone else in our squad I would replace him with - and his long throws in particular are a handy weapon to have in our arsenal. He is an important part of a very special team.