This was one of my all-time favorite books as a kid, and so when I found an extant copy in good condition on the interwebz, I had to buy it and bring this lost sheep back into the fold.
The story here abridges the second act of the 1990 TMNT movie, which is still, for me, the crown jewel of all Turtles canon. It does water-down some of the more "grown-up" aspects of the movie, such as the relationship between April O. and Casey J. (the latter of which makes no appearance), and merges some of the original animated series look with the movie storyline (such as April's hardcore 80s yellow jumpsuit and Shredder's comic book-esque samurai suit).
The highlight, in my opinion, is when Splinter makes contact through the Force with the Turtles — okay, maybe not the Force, but whatever kind of Zen Power they use to connect mentally and spiritually. In both the movie and the book, Splinter appears to them over a campfire, which to a Turtles-loving six-year-old was the coolest thing ever. This book represents that moment perfectly, and that sole image of Splinter in the fire (but NOT in the fire) still gives me chills.
Forgive the effusions of a fanboy, but having this children's book in my possession again is a dream come true.