Once you get past the color and sheen effects, there's one characteristic that I've noticed that I don't like. In certain circumstances, the ink tends to feather and bleed. It doesn't happen all the time, which makes me think it has something to do with the paper. Still, it happens about once per sentence and is noticeable.
Feathering aside, this is still a wonderful ink. The flow is smooth and steady, the color is deep and mysterious, and the intense sheen is a lot of fun. The bottle that Endless Stationery use for the Alchemy series is a fun design as well. The base of the bottle is convex, which causes the bottle to twirl around gently. I definitely wouldn't let it twirl with the lid off, but you also get a nice cork stand that keeps the bottle steady when you're filling your pens. It's a fun bottle design, but definitely not something that should influence anyone's decision to buy. The artwork on the box is also fun, with a detailed illustration of Poseidon next to a coral reef with a holographic effect on the box that shifts the colors.