I’ve been using this serum for about 6 weeks, and have seen a marked improvement. I started noticing it about 3 weeks of using it once a day. Not only is my skin brighter, it is also smoother and clear. I’ve actually received compliments on the quality of my skin, which hasn’t happened since my 20’s. I have always been an outdoors woman, and at 49 had begun to look a bit *cough* weathered. Having tried other vitamin C serums in the past, I had given up on them because they irritated my sensitive skin. For a little while I had some luck with a L’Oréal serum, but it began to lose its efficacy as I aged. I wanted something that would give me brighter and smoother skin, and address some fine lines I was developing. This serum was recommended to me by a dear friend who can afford to buy very pricy products (like..any products she wants). So I decided that if it was good enough for her, I should try it. I’m very glad I did. I will be adding other products from the CDB line in the future. The price point is attractive, and based on my experience with this serum, I expect them to work equally well (and if they don’t, I’m not out that much money!).I highly recommend this for middle aged, mature skin that has seen some outdoor weather. I cannot speak to how it would work on very heavily damaged skin, as I’ve been better with using sunscreen for the past 4 years, and think that has helped stave off deeper damage.