Indeed, I personally believe it's closer to 10% that have as severe as issues as I have. But to me, this is just an unacceptable number. With traditional controllers, it works 100% of the time, with Move, there's a big statistically significant number of people who have a big fuss getting it just right. Those people might still think the headache was worth it, however, but that's not my point.
I believe it's probably a bit higher the number of people who might have to do some quick fiddling before finding the "ideal" settings (like AndyD, for example, who mentioned he had to do some fiddling for EyePet, or that other guy who suggested he had to roll up his rug).