I've still got some creatine from when I tried that. It was pretty cool actually, my muscles swelled a bit and got firmer. I was stronger too. Could lift more, and such. Didn't help my running, but hey it was cool. Felt pretty good.
Unfortunately, the rumors of cramping are true. One day after a sprint if I recall correctly I got shin splints in both legs. Hurt pretty bad. And it stayed with me pretty much all season, no choice but to train and race with them. Went to a chiropractor/sports massage place and had this guy work on my legs every couple weeks or so. He seemed a little sadistic to me, but meh. I recommend lots of water, don't end up with this kind of problem.
Although the shin splints might also have been attributable to overdoing it. Went from a pretty inactive life to a nice amount of training pretty fast. So I don't know, but to be on the safe side just drink a lot of water. If you do it, I recommend the powder. Ridiculous shelf life, and tasteless.