Recommendations to others considering GNU Make:
Take some time to practice it a bit if you want to use it manually. Also I recommend learning make before learning other related tools like CMake or the autoconf, automake, libtool combo. Even if you don't ever write a line of a Makefile yourself it pays to know how to read one for debugging purposes. Review collected by and hosted on G2.com.
What problems is GNU Make solving and how is that benefiting you?
I use GNU Make personally to automate all sort of processes that produce intermediate files. Almost all my C/C++ projects use GNU Make (unless the size of the project is so small that adding Make becomes unnecessary).
I also use GNU Make to automate LaTeX compilations when writing technical reports and whitepapers.
I have even used it to compile Java projects using the LeJOS libraries for the LEGO Mindstorms robots since GNU Make is WAY easier to setup and use than Ant. Review collected by and hosted on G2.com.