My problem with Maki started during the Zenin massacre arc, and it just built on that during the Naoya fight.
Her moment with Mai was nice and everything, but their relstionship with each other and with the Zenin clan should have been explored in a 1-2 chapter flashback arc. Or an arc where they're prisoners before their execution and we see how the different clan members behave towards them and other women in the clan.
However, Gege was at his worst during that short arc, as far as his health goes so I'll scrath it to that being the reason.
Then we get the Naoya Curse fight. Maki is bland, and you could make the case it's because of Mai's death etc. But Gege goes so hard on making her Tojette instead of Maki that it's really hard to care or root for her. 2 characters (read "plot devices") are shoehorned into this arc so that she could "figure something out" and become a complete Tojizabeth. Minus the leeching off of partners, but maybe we'll get that EOS.
Her character could've been explored in a great manner had the arc not introduced her two personal trainers. Curse Naoya was enough of an opportunity to give Maki some sorely needed development and make her into her own thing.