I have been using this for about 2 weeks now and loving it. It's my first time trying a vitamin C serum and although it's too early to see any major improvement in my skin, I definitely think this will deliver amazing results. It has a relatively thin consistency and smells quite strongly of citrus (particularly oranges I think). As I am new to using vitamin C and this is quite a strong one, I have been using a bit of toner before applying and that has lessened any potential irritation. Even still, it will likely leave your skin feeling slightly tingly for a couple minutes, certainly not painful though!