Coke is by no means good for you. It also contains no Potassium as far as I can tell (reading a can right now). There is sodium in that, but most people in westernized cultures get more than enough of that already in your diet. Water is by far the better choice. Coke will dehydrate you both because of the caffeine in it which acts as a diuretic, and because it is hypertonic, or put simply the stuff dissolved in the water:water ratio is higher than that of our bodies, so our cells actually lose water to balance out the ratio.
The water/coke facts at the beginning of the article I am fairly sure are either exaggerated or totally fabricated, but I can't disprove them, mostly because I don't feel like taking the time to do the research.
Oh, and just about everything gives you cancer
And finally, I gave up sugary pops a little over a year ago, lost 30 pounds. We get an ungodly number of empty calories from pop.