A handy module, and pretty unique on CPAN for better or worse. Uses basic GD functionality which is generally widely available on most platforms. There's no real test suite, and the documentation is simplistic -- but to be fair, there isn't much documentation required. Just be sure to set GD::Image->trueColor to false if you've previously set it to true, or you're going to be fighting with black images until you get that light bulb.
This distribution comes with no test suite -- just the one default test.pl file that you would get with an old version of h2xs. Hence, it is impossible to run coverage analysis and get an idea as to where bugs might be lurking. (I have not yet tried its functionality.)