What I appreciate about this book is that details of many aspects of astronomical computations are clearly explained together with extensively documented full C++ source code and references for further information. As a bonus, extensive star catalogues are supplied, for use with, for example, astrometry.
C++ is *not* my language of choice, but the authors seem to have done a masterful job of using C++ features well, while avoiding obfuscation. Initially at least, I am translating things as I go into Mathematica, as a check that I am understanding what I am reading.
All in all, for getting under the hood, I think Montenbruck and Pfleger provide exceptional value for money.