Review (5/5): radiant skin
This is the only C serum that consistently leaves me with radiant skin, without causing oiliness or, conversely, dryness.
It is advised for use at night, because it will oxidize when exposed to light (and air). I prefer to use it under my sun protection during the day, for extra protection and radiance. If you would choose to do this, use just one pump, because any excess will eventually turn light brown (oxidation). At night I use Philosophy's Turbo C booster, which doesn't add radiance and does dry the skin somewhat, but it DOES lighten the skin, which UNT C does not.
With these caveats, I have bought at least ten bottles in the last couple of years and highly recommended this product. (My skin: mature acne-prone).