At the advice of someone, I purchased this hair color for gray. I also bought FO-TI so I won't have to do this again.
Anyway, the stuff is super easy to use. Problem #1: it is intense and it stained my vanity, sink and floor - I am working on that. I bought one box of the stuff. My hair is pretty thick when it is nappy and I ran out. Therefore, I am sure that one side of my hair is darker than the other. The color is very intense as stated earlier. I got black brown and now it seems like my hair is almost blue black; it was black brown pre-color.
Drying effects: I can't really be sure. The hair feels funny with the color on it. However, my hair is super nappy (6 weeks which is WAYYYY too long for me to wait for a relaxer) and, therefore, I can't tell if it feels funny because I washed it while it had too much new growth or if it is the color.
Gray coverage: I would have to think that it covers excellently. My hair is so dark I can't imagine a gray strand escaping the color.
I get my relaxer tomorrow and should know more about the true condition of the hair.
Overall, I am pleased because 1) it's quick and 2) the color took without any effort by me.