Brainwright is a company known for its colorful, innovative puzzles, and "By the Book" is not an exception. The puzzle comes in a sturdy box, in which you will find small replicas of 2 shelves, 12 books, a cat, and a vase. You will also get 40 cards with various challenges, ordered in terms of difficulty. Each challenge requires that you arrange some subset of the books (and possibly the cat) on the lower shelf, so that the upper shelf can be placed flatly on top. This task is just as fun to do as it sounds, and the cute design of the miniatures makes the toy hard to put down.
Unfortunately, despite the interesting idea and masterful execution of the puzzle, the challenges themselves are rather poorly designed. Most of them have multiple solutions, and even the hardest ones occasionally can be solved by using very simple logic (find two books with the same height and place the others in-between). Also, the constraints which are included in some of the challenges, e.g. book A and book B must not touch each other, are often unnecessary and frustrating. Considering the low number of problems to solve and their overall easy difficulty, one can go through all of them within probably an hour.
Ultimately, it is very hard to rate "By the Book". It scores high in terms of originality, design, and sheer fun, but scores pretty low in terms of logic, which is crucial for puzzles. Overall, I think it will be a good addition to your collection, especially if you have younger children around. However, do not expect any considerable amount of challenge from it.