Is this coat warm enough for deep winter?

It is an insulated puffer with a hood, so it handles typical cold days and layering. For sustained sub-freezing weather or long time outdoors, a longer parka with more fill will be warmer.

How does it compare with a down puffer?

Synthetic insulation like this is heavier and less warm per gram than down, but it keeps working when damp and is easier to clean. Down packs smaller and feels lighter for the same warmth.

It is a short puffer that ends around the hip, so it covers the torso but not the thighs. That makes it easier to move in than a mid-length or long coat.

Does the hood come off?

The hood is fixed, so it stays attached. That means no lost hood and no gap at the collar, but you cannot remove it on milder days.

How should I care for a synthetic puffer?

Follow the care label; most synthetic puffers wash on a gentle cycle and tumble low with dryer balls to restore loft. Avoid fabric softener, which can flatten the fill.