If you are interested in the history of the English Language, word derivations and English generally I strongly recommend this book. I would have given it 5 stars but knocked one off because at times, especially in the first few chapters, Bragg can get a bit tedious. His writing style is very odd too. I'm not saying it's bad, just odd. It's as if he is slightly off-kilter with the world. Also some of his sentences go on for ever with little punctuation, which struck me as peculiar given that Bragg is a consummate intellectual and is writing about English!
Nit-picking aside the book is a great read. It is full of interesting history and, especially in the latter half of the book, full of fascinating facts you always wanted to know about words but couldn't be bothered finding out. Such as the reason for expressions such as 'the Real McKoy' and 'Maverick'. Why Americans pronounce every syllable while us Brits tend to clip vowels as in 'Cem-e-ter-y'(US) and 'ceme-try'(England). How Kangaroo, supposedly, wasn't actually the name of the animal but the aboriginal for 'I don't know what you're talking about' when a native was asked for it's name in English. etc etc
If it's quick fire facts about the English language you're after I would recommend Bill Bryson's 'Mother Tongue'. It is an easier read and has more humour. Bragg's book goes into much more depth charting the progress of English from it's very beginning up to present day America and Australia. Not as readable as Bryson, his style more lecture hall than matey, but definitely worth it.