FIRST is awesome. I was the main programmer/electronics man my junior and senior years of HS (2005 and 2006), it was more fun than any other club/team I did. The competitions are insane, you won't ever find more geeks in one place, heh. The atmosphere is very competitive, but at the same time there's a comraderie between participants and teams. For instance, I helped a team from a neighboring high school with their program, then went out and dismantled (seriously... we got disqualified) their robot a few rounds later.
I live in New Hampshire, where FIRST was founded, so Dean Kamen makes his token appearance/speech (in the same denim shirt) every year. The kids WORSHIP him - it is incredible. I was never particularly fond of him, especially after the segway flopped, but I have to say-- that failure is far overshadowed by the success of FIRST as far as I am concerned.