What dosage have you been taking? did you do the initial loading phase? This is not always required and some people believe it can strain your renal system i believe it is. The side effects you should be noticing are
Increase in strength (variable, but compound exercises tend to benefit the most)
Increase in weight (the is believed to be from water retention as the body trys to dilute the creatine in the muscles)
Increased endurance during exercises (in the sense you will be able to do more reps than usual, although there is some evidence that it can increase you CV ability aswell.)
You'll need to drink more during the initial period of loading due to the increase in water retention, you might also notice you pass more urine aswell because of the more fluid you're drinking
And POSSIBLE increase in recovery time, although this is debatable but the science is that the creatine will create the perfect enviroment to produce muscle when combined with fast assimilated whey protein.
As for the barely noticable increase in strength is possibly due to the fact that your Phosocreatine (creatine after body has stored it) stores were infact quite high already.
Try
www.Bodybuilding.com
Its an awesome site for information on supplements, and creatine is the most studyed supplement on the market (maybe except roids)