I know it doesn't fit all of your criteria, but it you're interested in SF book reviews, you should check out . It has been the best single source for SF book news for decades. The magazine reviews dozens of books each month. Unfortunately, they post only a few reviews to the web, and digital issues (pdf, mobi, & epub) have been available only since January 2011. The website also has:
Beneath that, we have our Autumnal 2015 edition of news, convention reports and book reviews. There's something for everyone be they into SF books, cinema and/or TV with: SF author, film, book trade, science news, and it includes the season's forthcoming SF and fantasy books listings. You can also check out the . In addition there are a few specialist articles and over 40 stand-alone SF book reviews.
A massive collection of SF book reviews with 5-star scale ratings
*Hall, H.W. . Bryan, TX: The Compiler, 1970—. Annual guide designed to identify and provide bibliographic access to SF book reviews, both for primary and secondary literature. The first four volumes have been superseded by Hall's (q.v.). Vol. 5, 1974 covers 1,310 books in 2,260 citations; its format is a simplified version of Hall's cumulative index. Directory of magazines provides identification of codes used to cover the source of reviews. The main arrangement is alphabetical by author, subdivided by title. Although a publisher is given, dates are omitted in the annual sequences. Alternate access is available through title index. Vol. 6, 1975, covers 3,101 reviews of 1,474 books in the same format.