A lot of people constantly say they hate this manga. But...for me it is honestly one of my favorites! Heres a shortened version why:
STORY: The story is pretty good. It is a typical magical girl plot and it is kinda like a better version of Little Mermaid with more romance.
ART: In both the manga and anime the art is outstanding. Perfect 10 cause it soo kawaii! There is no flops in the character design whatsoever.
CHARACTERS: The characters are great! The 3 main protagonists are each different with their own personality and their own individual struggles. The villains in the first part of the book are more entertaining that the MMPPP Pure villains.
ENJOYMENT: I overall enjoyed the manga as well as the anime. There are alot of fillers in the anime and repetitive battles with the villains. The manga shortens that and conveys the story in 7 volumes. It is also pretty good in terms of comedy and romance. The transformations are a little different in the manga but it still shows there changing from idol to human to mermaid.
OVERALL: Overall, I recommend this manga as well as the anime. Do not listen to the bad reviews unless you are not a fan of the Magical Girl/Romance genre. Any Magical girl or Romance fan would overall enjoy this.