How is Whey Protein Isolate a Good Supplement?

http://www.energyfirst.com/whey-protein-isolate : Whey protein is a good source of protein, as it contains the highest quality of protein. It is a first-class source that has branched chain amino acids, which contains the highest levels of any natural food source. Being used by lots of people, whey protein is especially good for athletes and for body builders.