I have looked forward to and enjoyed very much each of the new books in this series, and this one did not dissapoint, but I do have a couple of quibbles.
Firstly, yes, like other reviewers I missed the extra 100 or so pages, it was too short, only because I enjoy these books and so want them to be at least as long as the last ones.
But my big dissapointment is...why, why, why, before the series is complete, change the cover format? It was the different and not mainstream cover of The Spooks Apprentice that caught my eye and made me pick it up and bye it, and as a collector of childrens hardback books (the ones I like anyway) I have looked forward to completing this good looking set. THEN THEY GO AND CHANGE THE COVERS! When I first saw it advertised on Amazon I thought it must be an American version, but no, it wasn't. Why didn't they wait until the end and then if they wanted to they could have re issued the books with the new covers. I was not happy!
I wonder also about why the author has either put himself under so much pressure or been put under pressure from his publisher (I suspect the later) to write two additional books in addition to carrying on with the series. Why now, and is that why the Spooks Sacrifice was shorter? Why not finish the series and then write the two add on books. Fortunatlely, it didn't affect the quality of the writing, there was just less of it. I hope that the next book is a thicker one...real shame though about the cover change, although I guess children will like the new pictures, I'm a 43 year old child and I prefer the old covers, so there...whoever made the change I hope a big scarey boggart comes along and sits on your head.