Retinol is notoriously a harsh product on skin. There is a particular process to follow in introducing retinol into your skin regime - it can create redness and irritate skin.
When introduced slowly - skin was visibly smoother and more even in skin tone.
It was effective in reducing fines lines that I have watched creep onto my skin over the years.

For someone with "problem" skin, I would recommend this product. For me, with less temperamental skin, fairly even in tone and texture, the serum was able to smooth out both aspects and maintain a radiant complexion.