My experiences with the RPGA have generally been pretty positive.
I joined RPGA in the late 90s, mostly to get Polyhedron. In 2001, some friends were planning on playing various RPGA games at GenCon, and so I registered and played RPGA stuff throughout that con (the first time I'd ever actually played RPGA games). While I didn't like Living Greyhawk much, I really enjoyed playing Living City and Living Force.
A few weeks later, I discovered an online RPGA community, dedicated to playing RPGA modules online (using chat rooms). Though that group, I've made friends with dozens of other gamers, and we have a core group that plays various RPGA games together online, and gets together at GenCon or Winter Fantasy to play face-to-face.
IME, the campaigns that aren't run by RPGA HQ have been more fun.
- I've played every single Living Force module, and while I'm looking forward to the finale next year, I'm sad that it looks like there won't be a follow-up RPGA SW campaign.
- Living Death is also very enjoyable, though it's a bit harder to find a table, even online.
- I've just started into Living Arcanis, which is a fascinating setting.
- I played all the Living Dragonstar modules, and was sad to see that campaign go, too (when Fantasy Flight Games pulled the plug on the game line, that was the end for LDS).
- I enjoyed Living Spycraft, though I found it hard to keep up with all the rules options, and "gearing up" was always a pain.