Tha Don

its fine, as long as you are getting plenty of protein from other sources, personally i wouldn't want to be consuming more than 50% of my daily protein intake from ANY single food source

i also consume plenty of whey shakes (around 6 scoops a day right now), but 4 of them bracket my workouts, and the other ones compliment my eggs (in the morning) and cottage cheese (before bed), remember whey is to be used as a 'supplement' to an already solid diet, i wouldn't advise living off the stuff!