Only thing i would say is that they are quite long....I bought a small and I have long arms for my height (6"2 wingspan and I am 5"9) so they fit just about right, but i could see someone with shorter arms having a problem with the length.
In terms of performance they are top notch, could not feel the wind at all.
This is probably the best item of clothing I have bought. Castelli always seem to get it right. I wore it for the first time today, it was about 55 degrees and pretty breezy. I wore this with a thin sleeveless baselayer and the nano flex arm warmers, and to be honest was a little warm! This is going to be perfect later in the winter when it gets below 50