Creatine remains a staple for many lifters. As with anything, there's no measurable consensus on it's efficacy, but more people seem to get good results with it than not.
Also, as with many other supps, if you take too much of it, it will tax your kidneys and liver. But I agree with spent, any more than 10 gr per day is a waste. Long as you keep the water up, sides should be minimal if any.