Sunday Riley Good Genes Treatment can be used as either a serum or mask. I have not tried it as a mask, but I can tell you about its efficacy as a serum.
Good Genes Treatment is a winter product. It is very moisturizing, which may cause oily skin during warmer and humid times of the year. It smooths and plumps, although it did nothing to improve blemishes and unevenness in tone. It didn’t add any radiance to my face, either. Again, I still prefer Murad’s Advanced Active Radiance Serum or Philosophy’s Time in a Bottle.
From my preference for these two, it seems that my skin likes vitamin C, which Good Genes does not contain. However, your skin may be pining for other ingredients and Good Genes may deliver. I recommend this serum for people with dry skin.