I have six cats and five do react to it. One just rubs his face along the toy and goes all squirmy (very technical term!) and others are more hyper with their eyes dilating. Then they just flake out usually. I also have some catmint in a pot in the garden and that is a very popular spot with the cats.
An alternative to catnip is honeysuckle - some cats that don't react to catnip may react to honeysuckle.