The fabric breathes well, pockets work as one would expect, and the fit is great if you get it right. Ignore Castelli size charts and size up one. I am bigger than a typical pro but at 6 foot 155-160lbs I think I am in decent shape. According to the size chart, I would be a small, but medium works best. Arms fit snugly and do not move, and the torso conforms to my shape while allowing room to move around on long climbs when I am in and out of the saddle. One thing of note - I would say at my height the jersey tends to ride up and leave your lower back area exposed when in an aero position. If you don't wear bibs this jersey may not be the best choice.
This Jersey is a must buy!!! I have multiple Castelli jersey's and this is my favorite one. It does fit a bit snug. Best to buy a size up. Sometimes i forget im wearing a jersey at all asthe material does a great job to dry perspiration. I will definitely buy another.