A well-made jacket
I haven't had a chance to ride this in winter temps yet (it's June; I'll update the review in October), but I can comment on the fit and materials.
The jacket fits a little bit more loose than the jerseys, presumably to aid in layering. I don't think the jacket will billow out in the wind very badly even though I sized up, but since winter air is denser if you want something more aero then you may want to stick to your true size.
The jacket's as functional as a jersey, with three pockets in back. There may be little point in storing anything there besides your cleat covers in cold weather, though. Unless you like eating frozen bananas and clif bars. The fabric of the jacket is really dense and designed to stop wind. The high collar fits snugly and the sleeve openings are pretty narrow, so not much is going to get in. If you start overheating, about all you can do is unzip. But if the material on the back functions like that on the Transperante jersey, then it will allow heat to dissipate. But I don't know yet if that's the case. So a lot of questions unanswered, but I'm almost looking forward to the onset of autumn just so I can try it out! Almost.