I have the sweater orders in XS and it fits very well. It could be longer on the arms a bit, but I also have pretty long arms, hence the sweater is perfect from fit ago and has a nice interface (slightly fitted, perfect length).
I usually wear a size S, I think if the sweater is not too slack, then you should order it one size smaller. But if you want to pull over on him, for example, long sleeve shirts, that comes with the normal size and back.
The price-performance ratio, I find it very good! Comparable sweaters usually cost more and more for you then still annoying logos / trademarks / logos on it.
I am very happy and give 4 stars. Had the sleeve 2cm longer, there would be 5 stars from me!