See, in Ubuntu, I do 'sudo apt-get install gcj', hit enter twice (to bring in all the dependencies), and a little while later I have gcj up and running on my system.

I don't doubt it needs hacking to get running; I probably wouldn't want to install the latest release from source. However, when you have the package maintainers of two distros (Debian and Ubuntu) on your side, things get a bit easier.