One Red Bull has the caffeine of one cup of black coffee and 7 teaspoons of sugar. The caffeine content is about twice, and the sugar content slightly less, than a can of classic Coca Cola. See link below, also has a link to sugar content.
I don't like the taste of the stuff personally. Then again, I don't usually drink sodas either. 10 Red Bulls a day is like 70 teaspoons of sugar. I can't imagine how that doesn't put you at higher risk for obesity, diabetes, etc.
Caffeine Content of Drinks