Yogurt makes a great snack, breakfast, etc. It is an excellent source of calcium, and the probiotics are great for the digestive system. Most yogurt targeted to children is horrible - full of sugar, HFCS, artificial colors/flavorings, etc...not much better than giving them candy.
Instead of being lured by these colorful products, I buy plain Dannon yogurt and add goodies to it - a tiny swirl of chocolate syrup, vanilla, fruit, cereal, etc. It has half the sugar of Trix yogurt, and no funky additives.
I try to teach my kids that in most cases, the food that is marketed to them is usually not good for them. Commercials and cartoon characters are just a plot to get your money!