No Guarantee
The only downside to CG OCS (if you are committed to the CG that is) is that there is no guarantee that you will get a flight training slot afterward. On the other hand, there are some who get flight training directly out of OCS, and historically in the CG there aren't enough applicants for flight training, so your chances of getting flight training are pretty good. Particularly with some flight time and some ratings in the bag. Many are put off from applying for flight training because of the extra commitment that goes along with it, so there are usually pretty good odds at the pilot training selection boards.
If you are interested in serving your country as an officer and then as a pilot, the CG may be the way to go. As Saab, 80 and BrownTail have said, it is a great way to go and often you have the chance to fly both fixed and rotary wing aircraft. You many not get to choose right off the bat which type you get, but don't despair because many CG pilots go from rotary to fixed or vice versa sometime during their career. (Only the best ones get to fly Falcons the whole time however!)
You will fly some pretty sofisticated aircraft in some of the crummiest weather imaginable and more than likely save a significant number of lives during your career (and not just those of you and your crew!). There are some downsides and a fair amount of BS to put up with, but it is a great way to have Uncle Sam pay for your flight training and experience, sevre your country, and make a difference in many folks lives. You will also get to work with some very fine, dedicated people who are commited to helping others and completing their full time mission every day of the year.
Good luck.
FJ