Well, I do like Mason for a simple "CGI environment". It's between plain mod_perl and something like Catalyst and does have some nice concepts in my opinion. And the setup isn't that complicated either...
While I like Mason, and fully agree that it offers some very useful and clever concepts, I have to disagree if you are implying that it's easy to install. I have never had a Mason install go without hitch (and I've installed 20+ RT systems).