This is another TY Lee ink exclusive. Li Yu is yet another scented ink. It smells vaguely floral and I do not really enjoy it. Thankfully it isn’t a strong scent. Li Yu can be a deep dark saturated black ink or a shading grey ink. It all depends on your nib and how wet it writes. It is a rather lubricated ink and I enjoy that property.
Frankly for a store exclusive ink, I don’t see anything special reason why one should buy this ink over something else similar. Yes, it is water resistant but there are other inks that have the similar property too. After all it is black or grey depending on your nib. So your mileage may vary with De Atramentis Li Yu.