Its a huge grid, which makes the searching take longer.. The colors and objects are not appealing to ones eye. Its a take of Bejewled that seems like it's from the 90s. Meh.
Frantically swapping the sea creatures for a higher combo score is indeed quite addicting and this without doubt is one of the better puzzle games here.
The only thing I don't really understand is why you didn't combine your game "Sea Jewels - Hooks Gold" with this one,as the gameplay mechanics are largely identical (with the exception of the "Shoot" command and the world map).
In fact, "Hooks Gold" with the sea creatures from this game as alternate (unlockable) skins would imo be better than releasing both games seperatly.