Creatine will also make you a moody bastage and shorten your temper.
That is not a side effect of Creatine. Creatine is a natural substance. There are high levels of it in red meat already.
With that said, people under the age of 18 should not be using it.
Creatine will gain you muscle. The initial gain is water but continued use with a good workout routine will show solid muscle gains. Unless you are already maxing out your workout, there is not much point. Don't start off working out and immediately start taking creatine.
Good read on it:
http://www.menshealth.com/nutrition/creatine-side-effects-what-it-what-it-does
I am a HUGE fan of protein. 100% Whey protein. When I was working out regularly, I found taking a protein drink within 30 minutes of working out GREATLY helped my recovery time and I was also not as sore.
Also, "bulking up" does not reduce flexibility. Many athletes bulk up that need flexibility. Maintain your stretching.