I've just started taking it. I've always been of the school of thought that supplements are stupid except for protein which is just easier to consume (but no better if not inferior) than cans of tuna, chicken breasts, yoghurt, steak, etc.
I am a man who values an open mind and after reading about it I gave it a go.
I take the same does as the guy above at breakfast and after workout. Only because it is so bloody cheap. All the research says 5g after workout is all that is needed. Why do I take 10g a day then? Because I'm experimenting!
Two things I will say about creatine.
1) Its cheap - worst thing that could have happened to me was that I spend a couple of dollars on some 'experience'.
2) It worked for me. I noticed a difference in two weeks. I plan to take creatine forever with my protein shakes.
By this I mean I've been putting in the effort and adding that extra few pounds to the bar or going for one more rep and being succesful. Some of this is hard work on my part and some of this might be the creatine.
I have always stayed well hydrated and noticed no ill effects with creatine (because I already drank lots of water).
Go buy some creatine monohydrate (forget about the other kinds).
Google is your friend - don't trust me, go and do some research.