I actually really loved this product. I have oily hair so I usually don't use serums but I thought I'd give this a try (that's what birchbox is for right?!?) and it totally changed the way my hair was. I used just a small drop and instantly my hair felt smoother and softer and I noticed my hair was much shinier after drying my hair. And my hair stayed straight all day too!
One negative - I used a spray-in conditioner that I typically used everyday and after letting it hair dry a little bit, I used this serum and my hair became super oily earlier in the day. I've definitely learned to use one or the other - not both on the same day.