I'm 6'2" 165 lb and wanted a jersey that was loose fitting, but not flapping around in the wind, and long enough to cover my torso. I ordered this Castelli Classifica in size XL and it's a comfortable fit. The stomach area is too baggy, but I'm okay with it.
I've worn it on one 3-hour ride and it was very comfortable. The quality of the zipper is really nice. I also like having the zipper pocket on the back for my wallet.
For size reference, I also have the Castelli Gabba Jersey in size XL, and it is a little loose in the waist and snug in the chest, shoulders, and arms.