While the stated goal of a treatment of theoretical and computational chemistry without irrelevant mathematical details is admirable, this book falls far short of its ambitious goals.
The thinness of the book, rather than evidence of concise exposition, leaves much to be desired in its selection of what mathematical details are omitted and what is left in. It is far too simplistic to the point of misleading, Even many of the pictures, while certainly colorful, are often banal and unproductive (Figure 4.1 is a prime example of a complete waste of ink).
The book is unfortunately also rife with glaring mistakes. One particular egregious example is the use of the term 'molecular dynamics' wherever 'molecular mechanics' is meant, resulting in incorrect conflation of these concepts. Poor notation which fails to distinguish between states as kets vs. their position-space representations gets the authors into trouble, especially when writing expressions involving gradients, or worse, using kets in their exposition of molecular mechanics! Another fundamental error is the explicit use of a time operator when discussing energy-time uncertainty, which is wrong since energy-time uncertainty does *not* follow from the usual operator commutator relationships such as the one used to demonstrate position-momentum uncertainty (as explained in A. Peres's book and many others).
In conclusion, save your money and get another book. It is too full of errors, frivolous details and misleading 'derivations' to be worth serious attention.