We love the Jack Black line. My husband normally uses the All Over wash on his hair and happily agreed to try this. It is similar in affect, in that it leaves his hair clean, freshly scented and moisturized, which he needs since he doesn't use conditioner. He washes his hair at least 5 X's a week and this does not dry out his hair. I do believe it is largely due to the removal of sulfates. The tea tree is a nice addition, promoting hair health/growth. It's hard to comment on how well this thickens since my hubby has short hair, however his hair does look great. This would be a product that he probably wouldn't buy for himself, but I would buy for him during holidays.