What it is: Waterbased makeup that comes in liquid form.
Availability: At many costume shops (check in your area). Often sold widely at Halloween.
Cover: Highly pigmented in most cases.
Cost: Usually slightly cheaper than cream.
Wear: It cracks. At least all the kinds I've used do. Some will wear for a while before they crack, some crack a very small amount, and some, like Mehron's Liquid, crack a LOT. (However, their Fantasy FX seems okay. It only cracks a very little bit.) Also, it often feels like a hard shell on the face if you apply it a little too thickly. (At least it feels that way to me.) The problem is that as the water evaporates, it leaves all of the solids behind, and they turn into a hard coating over your face. When your face moves, it cracks the coating, and you'll see little lines in it, and sometimes small pieces will start falling off.
If you're just experimenting with different face patterns, or you're on a budget and are willing to sacrifice some comfort and appearance, this may be the makeup for you. It won't hold up to long wear, and you may find it very uncomfortable as it dries and cracks. The appearance is fine from a distance, but up close, it's easy to see the cracks in the surface. It is good, however, for just trying out a face, or if you're creating your own cat, it would be great for experimenting with different ideas, because it generally washes off easily, and you wouldn't be wearing it very long. For long wear or 'serious' costuming, however, I would not recommend it.