Do a search, this question has come up many times.
The potential for quick, free hours is not good in CAP generally, but the rental rates for proficiency flying or time-building are very good. I can fly a 2003 C-182T in CAP for about 43% of what it would cost to rent that same aircraft down the ramp from an FBO. There is an increase in red tape to be had for such a deal, tho; you have to wear a uniform (flight suit, etc) when flying, you can't take non-CAP members up with you, and you can't leave the state without approval from the wing (state-level) commander. After you've been a member for a year, you can use CAP aircraft for getting your instrument rating, and once you become a mission pilot, you can use them for getting your commercial or CFI tickets.