Star ratings are a pretty crude way of summarising the quality of books, but it is useful to present a very simple indication of the thrust of a review before the reader looks at it. In newspapers, reviews usually include a byline that performs this function; a star rating is as good an equivalent for this as any in an online review.
My star ratings are derived from a mixture of what I consider the objective quality of a book, how much I enjoyed reading it, and how rewarding I found it. The distinction between the latter two qualities is significant. To take the examples of two "four-star" books: Hermann Broch's Esch oder die Anarchie is a rewarding, intellectually stimulating read, although a challenging one. The Hound of the Baskervilles, meanwhile, is an enjoyable work that is easy to get through, and entirely successful on its own terms - but it's not a novel that offers much food for thought.
Therefore, often, books of widely differing literary importance will all get four-star ratings. The best books aren't invariably the most enjoyable. So it may seem absurd that I give Simon Armitage's quaint memoir Walking Home the same rating as Anna Karenina... But I can't in honesty rate the latter novel as a "near perfect" five-star read when stretches of it bored me.
So what is a five-star book? One that has uncommon artistic or intellectual ambition; that wholly or mostly fulfils that ambition; and that ignited a response in me that went beyond mere appreciation. That doesn't mean the book is without flaws, or that it is better than a four-star book. Tess of the Durbervilles and The Unbearable Lightness of Being would not be on everyone's list of "near perfect" books, but they moved and stimulated me to a degree that I acknowledged instantly because it happens so rarely.
There are very few one-star reviews, in fact just one at the time of writing. Usually, a book that really isn't worth reading reveals itself as such in the first few pages, and therefore it doesn't get finished. Two-star reviews are thin on the ground for the same reason, although they are somewhat more numerous because occasionally a book I don't like has something about it that persuades me to persist with it (usually, the fact that it is short!).
Three-star reviews cover a wide spectrum, from books that entirely fulfil their limited ambitions (e.g. Graham McCann's about Fawlty Towers), through to laudably ambitious works that come a little unstuck (e.g. Eliot's Daniel Deronda).
Finally, there are reviews of books I couldn't finish. These don't have star ratings but are marked by .
Titles of foreign books
If I read a book in a foreign language, the title is in that language, with the English title in parentheses. If I read a foreign book in translation, the title is given in English.