The book itself is an intellectual joy. It is a series of mysteries, with some 'tween-wars political relevance, reminiscent of Sherlock Holmes, although a bit more austere, and, indeed, a bit more poetic. Chesterton was very much a man of his times, and his opposition to the Balfour Declaration is couched in language that it, alas, to our ears anti-Semitic. You must bite your teeth and accept this, just as you must accept Kipling's (or Mark Twain's) use of racially inelegant language.
This particular edition, alas, is rife with typographical errors, missing words, and misspellings, and I found it unreadable. By all means buy and read "The Man Who Knew Too Much," but NOT THIS EDITION!