Dark brown almost turns completely black when you let it sit the whole time. The second time I noticed that the color cream leaked, so you have to be careful with the packaging and maybe put it in a plastic bag if you're going to buy. I let it sit for 1 minute, and that was more than enough.
The applicator is super good, too bad you can't use it for the eyelashes, hence the lower rating.
Try coloring for a short time the first time, max 2 minutes. Then you'll know how long the color should sit next time.