its a filler wax. all it is going to do is lay down a layer of fillers and make it seem like it is a lot "blacker" and shinier.. in reality you are changing the black of the car and once it starts to wear off, it will look just like before.
nothing beats a good 3 step and claybar. instead of using a black wax on a black car, spend a day doing everything right (like a mothers 3 step system). of wash, dewax, clay, wash, polish, glaze, sealant, wax. and you will have a car that will look better than that black wax stuff will do for you, and it will stay that way for much much longer when you care for it properly.
if you like the way it looks, go ahead and use it, but i personally don't like the colored waxes, they are a gimmick at best, and literally change the color of the car.