Having worked with CMake, it seems more expressive than Make (meaning you don't have to contort it to make it do what you want), but it seems quite complex I the sense that I don't have a clear picture of its semantics, i.e. what's going on behind the hood.
cmake is a replacement for the autotools suite, not make itself. You're right that it can be tricky to use.
One advantage cmake has is that you can tell it to emit files for ninja instead of traditional Makefiles. ninja is very well optimized for the problem of parallel building.
Having worked with CMake, it seems more expressive than Make (meaning you don't have to contort it to make it do what you want), but it seems quite complex I the sense that I don't have a clear picture of its semantics, i.e. what's going on behind the hood.