I like the stuff, although I'm sure for some it is an acquired taste. It's not really meant to be a replacement for a protein shake, per se... just a substitute for something where you would normally use milk, but are carb conscious.
In terms of the proteins they use... well, it's milk.
Personally, I would use it with cereal or to go with a meal. If I was making a Grow! shake, I just use water.