It comes in a 16-oz cup and cost me $3.25.
The Frosted Lemonade was pretty smooth and thick, more so than some shakes, and was more slightly off-white than then the creamy yellow in the pictures (I wonder if this might vary by location or by who's making it).
Overall, Chick-fil-A's Frosted Lemonade might be your thing if you want a shake with a bit of lemon flavor, but if you actually want something that lives up to the name, you might want to ask them for more lemonade and less soft serve.
Nutritional Info - Chick-fil-A Frosted Lemonade
Calories - 330 (from Fat - 50)
Fat - 6g (Saturated Fat - 3.5g)
Sodium - 160mg
Carbs - 65g (Sugar - 63g)
Protein - 6g