I had bought this sweater for my two oldest boys. Although they have different physiques, I bought the same size(medium), and it allows for two different looks. One fits looser; he is able to wear a dress shirt underneath and it looks fine, no bunching or anything like that.  He normally wears a medium. The other prefers to wear it more snug with just a form fitting t-shirt underneath.  He also wears a medium but he goes for the tighter look. Both of them look fabulous whichever look they are wearing.  I also think it is best to try on this sweater because initially when my son held it up it appeared like it was going to be too long in the waist but it was just right.
As for the sleeves, they do not ride up and reach to the top of the hand. So far it launders well - no pilling or shrinking. Overall, a perfect fit if you normally wear a medium.