I agree with Lilruffian. YOu may want to increase the difference between the lightest lights and the darkest darks. Think of it this way, if you took a picture of it in black and white, would it read well? It's important to have not only variation in color, but variation is value (dark vs light) as well.
As you knowl, since I work only in b/w I am very much focussed on value. Working in color sometimes buffaloes me, though I appreciate it when others do the work!
Your friend will truly be tickled to recieve such a gift.