I used Boost Build for years, but I never figured out how to do anything but copy/paste our existing build files. I found scraps of documentation on Jam here and there, but it never made much sense when I looked at our code. I later discovered CMake and found it much, much easier to learn.

On an unrelated note, the best comment I have ever come across is related to Boost Build: https://github.com/openembedded/openembedded/blob/fabd8e6d07...