From an article in paidContent:
Media Source, the company behind review publications like Library Journal, School Library Journal and Horn Book, is launching a subscription-based site, BookVerdict.com, that aggregates over 300,000 reviews from its publications.
The site is aimed at book-buying librarians, though anyone can subscribe. It includes over 20 years of reviews, including starred reviews, “best” lists and Junior Library Guild selections. “This website extends the value of our reviews beyond print, offering librarians one highly functional yet agile tool to support collection development efforts, while bringing online access to professional reviews of books and media to avid readers everywhere,” says Ian Singer, group publisher for Library Journal, School Library Journal and The Horn Book.
More info, including subscription rates, in the article.