Parts of it are basically The Stories of English Lite. Crystal explores the successions of language critics in an entertaining fashion, but spends too long discussing the British National Curriculum. The whole book is basically an argument against the zero tolerance approach to English.
On second thought, giving it 3.5 stars for helping identify why I so dislike sentence fragments that leave me looking for the verb. Or rather, for identifying why I'd be looking for a verb that isn't there.
[Answer: really long subjects are hard to parse in English, so I hold that long subject in my head for the length of the fragment (which takes effort), don't find it, backtrack, still don't find it, etc. Lesson: avoid long subjects and pointless sentence fragments.]