Cold, very cold. Fingers will be numb before you can snap a few photos and batteries will drain out fast. My recommendation is to wear gloves with exposed fingers so you do not have to remove the entire glove. Watch out when traveling in the METRO as hanging camera on the neck is not advisable. Snatch thieves will cut your strap and run off just before the METRO door closes.
Places of interest will be the usual attractions. Champs-Elysees is particularly charming, unfortunately, summer is much nicer. L'arc de Triomphe, L'opera, Jardin des Tuileries, Place de la Concorde, Notre Dame, La Tour Eiffel, Palais de Chaillot, Sacre Coeur... these are the usual well known places. Sugges to focus on details, the way they dress, things they eat, small cafe, etc.