I kinda love it. I think the tone is perfect for the brand. "This shoe works if you do." is a natural extension of "Just do it." It's direct and determined.
And, really, those "toning" shoes she's so sensitive about? Maybe she wears them because they "feel good," but a lot of folks wear them hoping to get a workout running errands. If Nike can't poke fun at that, what can it poke fun of?