For those of you that don't tolerate whey, there have been few satisfactory alternatives...
According to this article on ergo-log:http://www.ergo-log.com/rice-protein-wo ... lders.html
the problem with rice protein is that although it has a good amino profile, it has a miserably low amount of leucine (the amino acid most responsible for activating the mTOR pathway, which activates protein synthesis).
There are two ways around this.
1 - Take a large enough serving of rice protein that the leucine amount increases to the point necessary for mTOR activation. This is the approach tested (and recommended) in the article. The researchers found that you need approximately 50g of rice protein for this to happen.
2 - Add leucine to the rice protein. 3g or so would be enough, although I'd probably add 5 just because I prefer the number 5. This would work if you didn't want to drink a mammoth serving of rice protein (it apparently tastes like satan's earthy butthole).
So there you go. I'd probably go with option number 2 because leucine is cheap as chips and your protein powder'll go further that way. The good news is that once you have the leucine taken care of (by utilising either approach above) the rice protein is every bit as good as whey.
This is great news for people like me who can't digest whey, and really it's good news for everybody considering the price of whey has been rising every year for a long time now, and looks set to continue to do so.
I should probably note that this is purely from a muscle-building perspective. I have never compared rice protein to whey in terms of health benefits beyond muscle building, nor do I particularly care to do so at this time.