I'm a freshman cadet with AFROTC, but I think this can apply to the Navy. Personally, I was really gung-ho Academy last year. I thought that ROTC was nothing compared to the Academy, but you get out of ROTC what you put in. I pledged with Arnold Air, and when we were done I could do twice as many push-ups (easily over 100), I could sprint faster than when I was in track, and I could run long distances faster than during soccer. Then this semester I started cross-training with Army ROTC and they taught us jui-jitsu, MOUT, assaults, recon, etc. All the challenges are voluntary though. In fact, I found out that I was only the third AFROTC cadet to ever do Desert Rangers with Army ROTC and the first to do the Ranger Run (a 12 mile run with a 35 lb ruck-sack), which was followed by a 13-hour Field Training Exercize. I guess last year they got inserted by Blackhawks for a two-day FTX in the boonies, but the HH-60s are deployed right now. Like I said, you get out of it what you put in.
It pays off, I'll prob get an F-16 ride this semester and I'll prob be an OPFOR at a Nat'l Guard training exercize in Little Baghdad in Yuma at the end of May. I have a friend at USAFA, and he hasn't gotten a chance to do any of this. Then again, my story probably isn't typical of most cadets (IE: I have been a lucky bastard).
I won't reitirate what everyone else said about college being fun as hell and the leadership/social skills you gain, but I can personally attest that I have matured (socially) more this year than all four years of high school combined (even though I was always trying to build leadership, etc.). I've also never had so much fun or worked so hard in my life. I have no idea what life is like at the USNA, but I do know I love ROTC.