As someone who had very thick hair until my late 30's, I know what thick hair feels and looks like....
I have used all 3 products in the Fibralogy line for 3 weeks now. Honestly, I can't say I have noticed any difference in the feeling of thickness in my hair. When trying the ponytail test, there is no difference....it's as thin as ever.
The conditioner completely melts into your hair. It's very hard to tell it's there, and really doesn't condition at all. My hair is tangled immediately when rinsing it out.
I feel a bit slighted by this new product. I mean, the claims are pretty mighty, but the results, not so much. I also feel a little gullible that I actually thought a shampoo, conditioner and 'booster' could actually thicken my hair, or provide the illusion of thicker hair.
My advice, spend your money on a good pH balanced product.....you won't find anything beneficial about Fibralogy except maybe, the fragrance.

I got it to review as a freebie. I don't care for the smell. It smells like I keep dying my hair. Also, I feel like it has made my hair really dry and frizzy. I like the idea of the booster, but the tube is too small for the amount they want you to use twice a week. Really disappointed. :-(