Three things determine whether a vitamin C serum works. This gets all three right.
The form is pure L-ascorbic acid. This is the version with decades of evidence behind it — for brightening, for collagen, for antioxidant protection. Most drugstore serums use a derivative instead and still call it "vitamin C."
The concentration is 10%, which is inside the effective range. Below about 8%, the evidence thins out fast.
The packaging is an opaque tube with a pump. L-ascorbic acid oxidizes on contact with air and light — that is why old vitamin C serums turn orange. A dropper bottle lets air in every single time you open it. A pump does not.
The ceramides are a real bonus. Vitamin C at a low pH can be irritating. Ceramides are the lipids that hold your barrier together, so this repairs while it treats.