Stryc and BA have both made excellent points. BA, you can absorbe those protiens, but because they lack anything resembling a complete amino acid profile, they simply count as worthless calories that cannot be used to repair or build new tissue. They just bring up one's calorie count. That gives us a good idea of what these companies will do in order to make a $. They use incomplete, worthless protiens to bring down the cost of manifacturing their product, and to bring up the protien count in order to trick us into thinking we are getting something we are not.
As Stryc said, protien bars will do in a pinch, but don't make a daily thing out of it, and don't think you are getting the same quality of nutrition that you would from real food. Protien bars are a marketing scheme by the suppliment companies.