I was deciding between this, Assos winter jacket, and Assos Ultraz jacket. I am extremely happy I ended up with this. It is very versatile - I rode 40 miles in it today and temps were between the high 30s and mid 40s and I was never cold (Assos winter base layer underneath). Wind was constant at 10-15 mph and I never felt it due to the awesome Infinium material. During a few efforts I heated up, but because of the inner vest, I was able to open the jacket half way to let some heat escape without getting cold. If you are considering this jacket and Assos’ offerings like I was, I’d say that thermally, this is between the Winter and the Ultraz. The Ultraz is really thick and insulated. Size wise, I am an XL in Castelli’s race fit jerseys and the XL in this fits me well. Initially, I did feel some tightness in the armpit area, but after I rode in it for a few minutes that feeling completely went away - almost as if I had to break it in a little. Finally, Castelli, I do have a few minor nitpicky suggestions if you read these reviews: I’d make the cuff a little tighter so it doesn’t bunch under gloves, use the two rear pocket concept on the back like the perfetto/Gabba line, and use the same style of zipper on the front pocket as you do for the internal vest so it lays flush with the jersey instead of dangling.
Anyway, if your considering buying this jacket for winter riding, just do it. You won’t be disappointed.