Amazon includes brief excerpts from media reviews and highly opinionated reviews from readers.
UO WorldCat can be surprisingly helpful in finding book reviews. Tip: type in the last name of the author and a couple keywords from the title (e.g. bacevich washington rules) and then limit your results (thru the choices in the left column) to Articles.
Magazines Fulltext provides reviews from general interest periodicals. Tip: in the first search line, type the title of the book. In the second search line, type: reviews
Literature Resource Center provides reviews, literary criticism, and biographies of authors. Tip: limit results to Reviews & News
Historic New York Times gives reviews from the beginning of the paper (1851) up until three years ago. Tip: in the search box, type the title of the book; in the Document Type box, select Review.
Readers' Guide to Periodical Literature is a source that provides citations to reviews in America's most widely circulated periodicals, from 1890 to the present. Print volumes from 1982 to the present are in Knight Reference AI 3. R48. Readers Guide Retrospective covers from 1890 to 1982.
Nineteenth Century Masterfile provides indexing to articles from English language periodicals and newspapers, with links to full text where available. Sample search: Dickens Bleak house