Colour blind? Not really. Colour-dim-of-vision might be a better term. Cats' eyes are better adapted to dim light than ours, and they have fewer cones and more rods in the retina. What is more, they have fewer visual pigments than we have, just as we have fewer visual pigments than most birds.

They also have less concentration of cones in any one area, whereas we have by far the majority of our cones in the yellow spot of our retina.

The cones in the eyes of cats and dogs are most effective in distinguishing blues and greens from other colours. Longwave light probably is not well distinguished by the eyes of cats. I would not generally be willing to swap my vision for feline or canine vision, but on the other hand, they might not be willing to swap their vision for mine. It is largely a matter of what you need and what you are used to.