Some people think it's a clumsy statement on female body image.
The video ad shows the building and implementation of the "thinnest vending machine in the world," which apparently works to showcase how "famously fit and elegant" Diet Coke is.
The ad goes on to show the machine on display in settings that haven't pleased commentators — between salon chairs; between treadmills at the gym; on Pinterest.
"Oh, hey there, ladies. Feeling fat? Of course you are. Don't worry. I've got some advice ... Get delicious, trimming
The Huffington Post also reacted: "Thanks, Diet Coke, for reminding us all that it's always better to be thin — even if you're a vending machine."
Others were quite taken with the campaign. Trendhunter, a marketing blog, called it "fun and unexpected," and AdAge named it a "Creativity Pick Of The Day."
The trend of diet sodas marketing themselves to primarily women is nothing new.
In 2011, Diet Pepsi released its 'skinny can,' a "taller, sassier" design that riled the blogosphere. This year, the company redesigned its can again, basically admitting that it was only for women.
See what you think of the ad, from ad agency Ogilvy Paris: