Buy again? Definitely.
(Please note that I'm reviewing this for its effectiveness on dark circles, not so much puffiness as I naturally have deep hollows under my eyes that I actually would like to fill up.)
I've purchased my bottle in summer 2019 and am now about halfway through, having used it daily for most of the time. I can't remember anymore how quick the effects were to show, but it must have been within a few weeks. A little bit of a blue undertone has remained there, but by now I suspect that that's just my blood vessels peeking through.
The solution has a very gel-like consistency, much like aloe vera. It goes on wet and slippery but dries down to a tight-ish matte finish quickly. If I apply too much, some creams or foundations have a tendency to pill up over it, but otherwise the slightly tacky finish makes a great surface to apply makeup over. The formula is fairly hydrating and I can get away without using moisturiser on top most of the days, but I don't rely on it (it's mainly for the dark circles).
The dropper bottle is not an ideal container for an eye product, but it's not terribly inconvenient either; I have adopted a technique of squirting a small drop of product on my ring finger, screwing the bottle shut with my other hand, then transfering a bit of product on my other ring finger and massaging it around my eyes.