CMake is painful to use for so many common things I find it hard to believe it's achieved the popularity it has. For instance, given the focus on out-of-source builds, the -H and -B options remain undocumented for vague reasons. The community has also sworn off clean builds for some reason. The most baffling part is how anemic the command line interface is compared to the scripting language. For a tool targeting the command line aware C/C++ communities, it's far too common to rewrite build scripts with awk/sed/perl because the command line doesn't have the options you need.
