As many other reviewers have indicated, this book is verbose and poorly organized, and clearly not written by people trained in mathematics. It seems pretty clear that the book is also written FOR the idiots, er, I mean, MBAs who manage mutual funds and pension funds. A tell: the authors use the bizarre approximation

ln(1+x) = x (there is nothing bizarre about the approximation, but the use of the logarithm gives much simpler derivations of much more widely applicable results). Since everyone has a calculator with a ln button, and quantitatively inclined people can compute logs pretty quickly in their heads, this is an indication that the book is targeted to mathematically unsophisticated people. Not being one of these, I cannot tell if the book is useful for them. I can say that this is the second finance book I read (the first being an older edition of Hull's Options, Futures & Other Derivatives with Derivagem CD Value Package (includes Student Solutions Manual for Options, Futuresd Other Derivatives) (7th Edition), since my first finance project was developing a market impact model. Everything G&K had to say about market impact was either trivial or wrong, but they did refer to the very important paper of Almgren and Chriss. Read that, and be happier.