Casein is a type of protein. There are several different kinds, most people have Whey. Whey is great for a post workout shake, or even a pre workout shake. Whey is easily digestable and quickly utilized. That is good, except thatsince it is used FAST, it will not keep you full long nor is it a good end-of-the-day shake.
A good thing to do if you use shakes throughout the day or at night, is to mix proteins. Using a whey/casein , whey/egg, even whey/soy mixture will help lengthen the amount of time it is in they body - making you full longer but also maximizing the amount of time it is in the body so the body can really use it to help rebuild.
Only time you do not want a mixture is postworkout. Your post workout protein should be straight protein and maybe some simple carbs - no fat or complex carbs to slow down digestion.