Casein protein is generally a better muscle builder, a better strength builder, and a better fat burner than whey. Besides its mushy texture making It very pleasant to drink compared to the watery consistency of whey.

PLAIN CASEIN

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, they're just a poor choise when it comes to doing the basic job of protein powders, which is building muscle.

UPGRADED CASEIN

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. This means longer hyperaminoacidemia for protein synthesis.

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 in their native form and intact. Manufacturing properly micellar casein is a complex, very sensitive process.

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, meaning not only does it increase protein synthesis, it helps prevent muscle breakdown during and after intense exercise. 

You buy cheap, you buy twice!