My son, Callum, got this book as a Christmas present and it goes everywhere with him (including to bed). If he doesn't have it to hand we get a chorus of "dig dig digger" until it's found. In fact the reason I'm on the site is to order a replacement as he took his book to nursery and failed to bring it home and it's gone awol - we have had many tears.
One of his first words was tractor but he has now branched out to diggers, lorries, dustbin lorries, cranes etc all of which he can recognise on the streets and attempt to say. Walking past a building site or driving along in the car has never been so exciting. The rhymes are catchy and easy to repeat and Callum is picking up more and more of them, including joining in for the 'shhh' at the end. I can't rate this book more highly - both Callum and I think it's fantastic.