A surprisingly versatile jersey
I won't rehash all the details of the jersey, but as you can see from the other reviews it is a very tempting idea to use the jersey as a jacket. But, really, if a proper windproof jacket is what you need then you might be better of with the Castelli Mortirolo. But this one I've worn by itself in 40 degree temps (on a clear but windy day) through the low 60s (albeit cloudy and in a soaking rain). Where I live a cyclist gets punished with wind on many days, so this is a essential item when the weather is raw. The thermal fabric in back and down the arms make the difference: they regulate temperature so well that I've never overheated. The windproofing is amazing and really helps take the edge off. As you can see from the picture, the jersey's a smart-looking thing. With a pair of Sorpasso tights or knickers, you'll look like you belong on a bike even if you can't figure out which part of your helmet goes in front.
Fit: Like with all Castelli gear, you will prosper if you size up. I have a 35" chest and noodle arms and a medium leaves very little fabric billowing around.