I'd never used a serum before receiving this one in my Birchbox. Though it took awhile to figure out how to use it without making my skin look dirty (I have oily skin naturally), once I did figure it out, it's now a core element of my night routine. I wouldn't apply it more than once a day, but the benefits on my skin have been wonderful. I've finally stopped breaking out and my pores seem to have gotten smaller. It's a worthy product if you can work it into your routine!