First impressions are that it is very nicely packaged in a simple bottle, so there's no fussing about how to open it or worrying about any leftover product stuck in an awkwardly shaped dispenser! When I pumped some of the essence on my hand I noticed it was very slimy, like an egg white. Because of this, I tried and failed to follow Cosrx's recommended directions for applying! I ended up rubbing about 3 pumps between my palms and applying it to my face in that way instead. It has no smell at all... I read some reviews which said it had a slightly chemical smell but I can't smell anything when I use it. For its slimy texture, it absorbs so quickly! I don't know what happens but my skin texture just felt a lot happier! There is a little bit of a cooling sensation as it absorbs into the skin too. It leaves a small but flattering sheen to the skin that makes it look and feel healthy and clean. 
After using it for a couple of weeks, I have noticed how quickly the product works. I now wait a few minutes for it to settle into the skin before applying anything on top of it, because it also controls the oiliness of my nose a bit. It also reduces redness of any pimples or spots within about an hour... I have never used a product that works this fast in soothing my skin before! My skin texture is a lot softer, especially after a good exfoliation, and it looks a lot better too. I've been using it every morning underneath sunscreen and the bottle is still very full... I think it will last at least a few months, which is fantastic value. The only disadvantage I can find is that it doesn't provide any sun protection or intense moisturising in dry weather, so it has to be used with another product. I will probably look into buying a Cosrx product for this. I will definitely be buying this again!