Carrot is ok and all plus she is super popular based on the last character poll which means Oda definitely did something correct.
However, imho she is not the best. The interaction between Nami and her are not that interesting or memorable to give her that much screentime.
What if you put Tashigi instead of Carrot with Nami in a covert op with the navigator to dig out information. The orange girl would not hesitate to use her charms to get what she wants and Tashigi would be embarrassed and shy when she tries it . When the danger comes, Nami runs away while the captain is courageous inspiring our navigator to stand her ground too. Honestly, that one scene in PH had more memorable character development for Nami than whatever happened with Carrot.