Perhaps the most beautiful dining room in London, the Criterion was once a tavern and then a large restaurant and entertainment complex, Victorian style. The spectacular gilt ceiling and marble walls were covered over during the war and only recently has this glorious room been restored to its full glory under the ownership of Marco Pierre White. The kitchen serves simple brasserie food with a wide, appealing menu. Examples are pleasant risotto with asparagus, but when the kitchen pushes itself a little harder it generally delivers e.g. a tian of crab with a tomato and saffron dressing. There is comforting food like smoked haddock, poached egg and colcannon.
For dessert try the extremely good lemon tart, a cut above the general level of cooking here. Service is erratic, generally well meaning but also sometimes disorganised. There was a good wine list, with choices like Riesling Cuvee Frederich Emile from Trimbach and the excellent value Guigal Cotes du Rhone, as well as a wide selection of New World offerings. The Criterion is never going to push culinary boundaries, but it is mostly reliable and is a great place to take visitors to London, as the dining room itself is so stunning. I have heard less and less good things about the food recently, so you might consider the nearby Wolseley as an alternative.