I can see how cats who never got used to crystals would hate them. I gave bags away as try-outs to friends, and they all said the cats were just not getting used to the litter.
One thing you have to remember, is to make sure you rake the crystals after a cat pees to make sure the crystals are absorbing the pee and it's just not sitting at the bottom of the pan in already 'filled up' crystals. second, you have to make sure to get round crystals, they're most natural to cats, the 'chunky' variety is much harder for them to get used to.
my marsh was raised at the breeder on crystal litter, so he doesn't know any other type, which makes it very easy for me to just maintain what he already knows.