Eh, I don't like it. It's not the concept so much[footnote]though granted, I'm not much a fan of retooling characters like this without good reason[/footnote], but the character design of the image. As repeatedly noted, she looks way too young, to the extent that I'd wonder if a male of similar apparent age could even be expected to have a full moustache, much less the bushy one we're all familiar with. And then there's the matter of weight (again, as noted priorly) and the general costume design, which strikes me as wrong for the character regardless of gender. Let's face it, at the end of the day, Mario's an Italian in overalls, practically the definitive 'work clothes'. And in the image we see "Maria" wearing a frilly dress...which is a more than a small shift, and an incredibly poor design choice for a character whose definitive attack involves jumping on the heads of enemies.
What I'm trying to get at, of course, is that at the end of the day this just feels less like "Mario/Maria" than it does a little girl whose mommy and daddy dressed her up in the colors of Mushroom Kingdom's hero. Add some age, some weight and more practical attire and maybe it could work, but the design in the OP...no.
