One of the most discriminating diners I know lit up like a marquee upon hearing that Boston has a branch of this Chicago favorite. The food is classic -- house-made patés, fresh baguettes, superb shellfish, salade Nicoise, Alsatian onion tart, choucroute, coq au vin -- but never boring. The house beer, an Alsace-style draft, is a good accompaniment. The casual, all-day French brasserie and bar fits well in this neighborhood, where shoppers can always use a break but might not want a full meal. It's also a good bet before or after the symphony, and it's popular for business lunches. The only drawbacks are the noise level, which can be high when the spacious room is full, and the uneven service, which ranges from solicitous to forgetful.