I can actually see why someone would find the game too "cartoony" because personally the design (excluding mechanical level design) and colours are not to my liking either (but they do fit a Mario game and it is a Mario game...)
She never makes it quite clear what cartoony aspect she considers irritating though, because if it's the 2D non-realistic aspect altogether, that'd make liking platformers rather difficult.
Then there is also the crap about how this works for her on the DS but not on a home console and by then it's pretty clear that it's not even the style that bothers her. The same old "want a little more from the graphics"... and no, I don't know what she means by wanting "a little more adult". Oh, maybe the wrinkles on that 3D Mario image.
