Shampoo and conditioners geared towards curly hair can surely help with frizz control and definition. Also there is certainly nothing wrong with trying them if you have curly hair, but there are also a lot of other good shampoos and conditioners that aren't specifically geared towards curly hair that work equally as well.
Products in my current regime: Nioxin Scalp Therapy Shampoo, ORS Replenishing Pak, Curls Whipped Cream, Curls Souffle, Curls Spiral Curls Cream, Curls Milkshake, Curls Quenched, BB(Bonner Brothers) Growth Lotion
If you're talking about drugstore lines, I honestly think they are not much different than the non-curly products from the same manufacturer. They just call them curly and give them different packaging.
And so am I. From reading labels, the drugstore ones do seem to have the same ingredients as the regular stuff. Also, a lot of products geared toward curlies seem to have silicones, as if every curly's hair needs that. I usually stay away from stuff labeled for curlies and go for moisturizing instead.