I feel she's an interesting character myself, I like her role in the story, social link and plotwise, her design looks awesome, and she actually says Fsteak which is not only a Hiimdaisy reference but also some clever localization on her original line in Japanese. Not to mention I find her cute when she gets embarrassed despite not really liking her poetry.
Honestly Minako is much more of a Mary Sue than she is, though that's just me not really liking Persona 3 that much in general and the Female route social links feel like absolutely trashy teenage fan girl fan fiction. I mean I get the protags are in general Mary Sues, Yu is certainly another case though in a more positive way, but Minako is just more taste like diabetes Mary Sue and Too Good for this Sinful Earth. For [tornado fang]'s sake, she manages to undo Shinji's death if you make the right choices, has social links with all party members unlike Minato who only has them with the females, her music is just peppy bubble gum trash, and don't get me started on Ken's route.
Marie's actually in my top 3 female characters in Persona 4 behind Chie and Naoto who kind of tie with each other and in my top 5/6 overall along with Aigis, Eriko, and Lisa Silverman. But that's just my opinion.