I received a sample of the skinceuticals at a local pharmacy in Germany and liked it, but I admit, I was too stingy to pay almost 60 Euros for the original Skinceuticals serum.
I ordered this product directly from the u.s. website of the company and I used it up, so I can´t say anything about the returning policy or so.
I paid about 25 Euros for 30 ml, which is cheap compared to the Skinceuticals, which costs about 45 Euros for 30 ml in the cheapest German online store I could find.
I have sensitive, dehydrated, acne-prone combo skin, which is sometimes flaky and patchy. I wanted much moisture to smooth my skin and make the dry spots go away. Another issue was a minimal ingredient list as my skin is sensitive and freaks out if I use too many products with too many ingredients. Basically, I searched for a very neutral and very basic moisturizing serum.
I received the serum and used it up, but I admit, I found it a little more sticky compared to the sample of Skinceuticals and it didn´t really sink into my skin. The serum surely did a good job of hydrating my skin and has minimal ingredients , which is a godsend for people with sensitive skin, who don´t want essential oils, too many or highly irritating ingredients.
I liked the serum and would recommend it to anyone, who is on a budget and wants to have a good hydrating serum.
The difference between the 2 serums is minimal and obviously the css is way cheaper than the Skinceuticals.
Personally, I decided to get the Skinceuticals, because I took another sample of their b5 serum with me on a beach holiday and used it a whole week with fabulous results, which I didn´t get from the css.
If you can, try to get samples from both serums and find out for yourself, which one you like better.
But I can definitely recommend the css serum as I had much more expensive serums from other brands, which were not as good as this one.