[Sumpter]

C++ is both mature and regularly updated. There are at least 3 solid compilers and the new features are aimed at solving real issues. Debuggers and analytical tools of all kinds are available for everything from performance profiling to automatic detection of issues of all kinds. This means the language is constantly growing to incorporate newer and better features.

Because of the above features, Satoshi Nakamoto chose C++ to be the base language of the bitcoin source code.