Rebonato addresses consequently practical implementation issues (although not coevering the technical details of the implementation algorithms - read the original papers for that!) that are frequently missing in so many academic publications. This makes it to one of my favorit books on my book shelf. I am looking forward to his next book on intrest rate derivatives.
The first edition (the one that I'm familiar with) does indeed contain a number of irritating typos, many terms are first used then defined later, and the figures in particular can be greatly improved upon (I think they were produced by `Excel', which is not the best tool to produce high-quality figures for a serious technical book), however such glitches are typical of almost all books of such size and technical level.
The mathematics is not entirely trivial, but not too sophisticated either (a typical university science/engineering graduate should be able to handle it easily), and the author makes a valiant attempt to explain all relevant concepts from linear algebra to probability theory (I have to add that I didn't appreciate certain fast tricks like dropping the measure `dt' from the end of certain equations `to lighten the notation'. By doing that, one ends up with the wrong equation!)
As the author clearly indicates at the beginning, though reasonably self-contained, the book is by no means intended for a first course on option theory. However, for readers familiar with the basic facts of options and futures (at the level of Hull's book), this is a great book to read. I personally learnt an enormous lot from a first reading. I highly recommend it.