Let's get the good stuff out of the way first... this shampoo (and its matching conditioner) is the best hair product I've ever used. A little bit goes a long way. The smell is absolutely amazing. It makes me not want to use any other hair products or perfume after because I just want people to smell my hair. After using it once, my hair was unbelievably soft. It had the perfect amount of moisture. I have only glowing things to say about whatever formula the geniuses at Davines created.
However. I bought these full size after getting a sample from Birchbox. I was SO PUMPED when it finally came in the mail. Aaand both my shampoo and conditioner were missing like a quarter of the product. It's pretty common for beauty products not to be full to the brim, but this was abnormal and, based on other reviews I've read, common for this product. When you're going to charge this much money for your shampoo/conditioner, leaving that much product out is unacceptable.
Bottom line: the tradeoff is worth it to me. I love this stuff and will continue to buy, especially since as I mentioned you only need a bit (and I have THICK hair). But I can't help but feel a little cheated.