I bought one now. If you want to have fun "Shiny hunting", it is worth it. One box had 15 packs (10 cards/pack) and had 3 shiny Pokémon, 2 GX and 1 prism star.Did anyone ever open a Korean GX Ultra Shiny booster box?
Because they sell for 23 € + 6 € shipping on Ebay, while the Japanese are ~70 € + shipping. However, if their pull rates are as bad as from other Korean boxes, there might only be 1 shiny card per box and then it's not worth it.