Have been using this product for about 18 months now, on conjunction with other Ordinary products. I use this in my AM routine after cleansing and apply the dropper to the palm of my clean hand (about 5 drops is plenty) and quickly rub with other palm and apply to face by gently patting in. The bottle lasts ages even though I know it looks a small bottle.
It feels like it is oily but it sinks into the skin very quickly. I then apply moisturiser and sunscreen and thats it.
There is no smell that I have noticed and I think it is good value and can be layered with other The Ordinary products. If you aren't sure what can be layered with this - just ask or go to the Ordinary website.