The bad part, unless you actually 'polished' the car, you can not remove swirl marks and scratches, but you can cover them up. The problem with that 'black box' is that it is simply an overpriced wax with actual black color pigment in it. When you wax, it fills in those rock chips, scratches, and swirls, but a few weeks later (depending on how often and under what circumstances the car is driven) it will look the same way it did.

If the car was polished and a good wax was added, you would have much better long term results.

What really matter is that you are happy, now that I don't have a black car to keep clean anymore, I am happy as well