There are plenty of studies comparing the muscle-building effects of casein and whey, with casein generally coming out on top. There are all kinds of reasons for this, but the main point is this: Casein is generally a better muscle builder, a better strength builder, and a better fat burner than whey. (See Casein vs. Whey: The Real Story.)
Most inexpensive casein protein powders are composed partially or totally of sodium or calcium caseinate, both of which the body absorbs fast like a bunny. As such, they cause a rapid rise of insulin. They also don't provide sustained levels of amino acids.
They're not a complete waste, but they're kind of anemic when it comes to doing the basic job of protein powders, which is building muscle.
If you want a casein-based, general use protein powder – one that does what's it supposed to do, i.e., bolster your daily protein intake for the purpose of muscle building – look for protein powder products that contain micellar casein. Micellar casein is composed of soap-bubble like molecules (micelles) that form a bolus in the stomach when consumed. That makes them digest really slowly.
It's really hard to make a protein powder from micellar casein – hence their relative rarity and higher price. You have to process it carefully and leave the milk proteins largely unmolested. Manufacturing micellar casein is almost like catching snowflakes in Maine and shipping them intact to California with a truck driver who stops outside a bar in the Mojave Desert to slam down a few tequilas.
It's worth the trouble, though, because micellar casein is the only protein that's been shown in lab studies to actually be anti-catabolic (Boire, 1997), meaning not only does it increase protein synthesis, it helps prevent muscle breakdown during and after intense exercise. Metabolic Drive® Protein contains an ample amount of micellar casein.