Juice, in general, is unhealthy. I only feed juice to my children once and a great while (maybe once every other month or so) and when I do you can be sure I won't be giving them these. Most of the Capri Suns have High Fructose Corn Syrup which I avoid like the plaque. Despite what Kraft and all the other high processed food companies want you to believe, HFCS is not natural and is not healthy.
High in sugar, no preservatives so it spoils quickly. If you want kids to drink juice "boxes" I'd recommend apple & eve, mott's, or welch's. Otherwise, I would stick to water and milk for little kids, or adults if you still like that stuff :)
I've read about the mold inside. Capri Sun has no preservatives, so it's best to be smart and keep it in a cool place, and dispose of anything by drink by date.
I am not a fan of any juice for kids, but mine still get some. Moderation is key.