Roy Keane's book is a masterpiece: The Second Half gives a startling account of his colourful career and reveals the hard-man midfielder's long-hidden good points ... Keane's book, ghost-written by Roddy Doyle, is an endlessly absorbing piece of work. It may well be the finest, most incisive deconstruction of football management that the game has ever produced

There is much in Roy Keane's new book that is thoughtful and self-mocking, insightful and funny

Keane's book - ghosted by Roddy Doyle - is brutal, amusing and self-deprecating, often at the same time

Roddy Doyle's works, mostly set in a fictional Dublin suburb, often star quietly frustrated everymen, and it's this book's achievement to make you see its mighty subject in that light

It is the dearth of integrity that makes Pietersen such a peevish, trifling character, and the surfeit that makes Keane so entrancingly epic ... the personification of honest to a fault ... he is as close as sport can offer to an Old Testament prophet. Heroically unconcerned with being loved, almost insanely devoted to telling what he regards as the plain truth, he may not always be engaging. But ... he stands out as utterly and irreducibly true to himself

The best things are the small things: regretting joining Ipswich when he discovered the training kit was blue; refusing to sign Robbie Savage because his answerphone message was rubbish; being appalled that his side had listened to an Abba song before playing football. The irrational, blistering intolerance is delicious. Keane famously detested yes-men; he created himself as the ultimate no-man. And he's still here

When Keane says anything, listening is usually the best option. He's scarily extreme, dangerously provocative, oxy-acetylene forthright ... and hugely entertaining ... Self-desctruction, self-pity, self-laceration - his latest unburdening has all this and more. His book reveals more flaws and admits to more mistakes than Sir Alex Ferguson did in his last literary effort - and Keane's is much funnier

The book is brilliantly constructed, rattling along at breakneck speed. And it makes a change from the standard sporting autobiography in being so hard on its principal subject. This is a book full of self-deprecation ... No self-aggrandisement, rather a ruthless self-examination

Keane's eminent co-writer, Booker Prize-winning Irish author Roddy Doyle, does a brilliant job. His gift for comedy and swearing, together with his wonderfully transparent style, not only captures his country man's voice but also adds some much-needed light and shade to the unforgiving business of being Roy Keane. It's not a sentence I expected to write but the account of Keane's triumphant first season at Sunderland is particularly uplifting