To locate reviews, search for the title of the play in quotation marks, and select document type 'Review.' You may need to add the keyword 'theater' in order to narrow results to reviews of performances.
To find reviews in the New York Times from 1851 until three years ago, use ProQuest Historical Newspapers. Try searching for the name of the show and the playwright or director in Advanced Search. Limit to Reviews under Document Type. If you don't find anything, try also limiting by date.