This book is a mess. The authors want to tell a story in a friendly manner, but first they spend over 50 pages of a 300-page book describing the basics of linguistics (phonology, syntax, language change). This will scare away readers wanting a friendly introduction, and for readers wanting a more meaty text these linguistic concepts are presented in far too sketchy a fashion to really prepare them for serious study. After that introductory chapter, the actual description of English over time is little more than the authors throwing out trivia without forming a coherent, smoothly flowing text. It feels like something cobbled together.
The chapter on Late Modern English is interesting. While anyone can notice that e.g. Jane Austen was writing from a different time due to her quaint vocabulary, I had never noticed some syntactic changes that had occurred in English only after her time. Still, there must be better historical introductions to English out there.