This has been one of my favorite Birchbox finds to date. I used the shampoo and conditioner samples months after my box arrived, and I should be kicking myself for all of the bad hair days I could have spared myself. I have curly hair (the unruly variety, not the pretty spiral curls) and the Nexxus shampoo and conditioner kept my hair from getting the usual frizz that rainy days typically bring. My hair was smooth and cooperative all day!
I can only recommend using the two products together as I haven't been rebellious enough to try only the shampoo.