It is not often you find a book which successfully bridges mathematics and finance, with the graceful consideration of the practitioner's issues in implementation. This is Hull for credit derivatives.
The math flows very well alongside a narrative which summarizes the story with terse reasoning. The math is not burdened with notation and is instead linked nicely with financial concepts. This is all reinforced with examples which bring out subtleties of pricing and market conventions. The author makes copious references to further reading, but does not make detours which would detract from explanatory cohesion.
The book can not be all things to all people, however, so some veterans to structured credit may find the treatment a bit beneath their level of expertise. The most appropriate audience would be graduates of math-finance courses who need a thorough introduction to structured credit as it is practiced in banks.