Perona is probably the most unique looking One Piece girl (that isnt supposed to be monstrous)
The face and dress are definitely very unique, and not like other female characters. But the body shape is still pretty similar to the normal girls. A little shorter I guess. It's certainly not a bad thing to stick to a style that works though. I think the similarities in his female designs just stick out a bit because of how different his male characters are, especially in the leads. None of them are remotely similar, but both Nami and Robin share a lot more in common. The perception is pretty strong especially when looking at those main characters over and over in cover spreads and lots of scenes in every other chapter.