I only have their down jackets and pants and a pair of Dynamo pants
I am tall with long arms and legs and quite slim.
I would say I find their sleeves to be on the reasonably long side, as long as almost anything else I have tried. The chest seems fairly run of the mill for width. the length seems standard as well to me.
Their pants are the best i have yet found, by quite a bit, nice and long and quite trim.
For me, they are as good as or better than any other mass-produced brand(haven't tried Arcteryx), even LL Bean tall L was about the same as MB XL, as far as long enough sleeves and baggyness of the torso.
There are staff and user reviews for many MB garments, check them out to get a better idea of the fit of the specific item you are considering.