Is this jacket warm enough for winter?

It is an insulated puffer, so it handles cold dry days and layering well. Without a hood or a cinched waist it is less suited to heavy rain or wind than a technical parka.

What size is it, and how does it fit?

It is labeled a medium, with a 20-inch pit-to-pit chest, 19-inch armpit-to-cuff sleeve and 25-inch collar-to-hem length. That points to a regular fit ending around the hip.

Does it come with a belt?

No. The belt is missing, so the jacket wears loose at the waist unless you add your own.

Is it good for rain or snow?

The quilted shell resists light wind and drizzle, but there is no hood and no waterproof membrane stated. For steady rain or snow, a hooded shell over it works better.

How does it compare with a new puffer?

Newer puffers often add a hood, adjustable hem and cuffs, and a stuff sack. This one is simpler and shows used wear, but the DKNY build and insulation are the draw.