Kate Upton, Carol Alt

Kate Upton may be one of the world's most popular supermodels, but her appeal isn't universal.

Supermodel Carol Alt, 53, told the Huffington Post recently that she thinks Upton, 21, is overrated. "What I don't understand with Kate is, like, what's all the hullabaloo?" Alt told HuffPo. "I don't get what all the hullabaloo is."

Quiz: Which celebrity is older?

Alt was referencing Upton's cover photos for the 2012 and 2013 Sports Illustrated Swimsuit Edition, and her presence in the magazine's 50th anniversary issue. She credited Upton's burgeoning success and popularity to her presence on social media. (Upton has more than a million followers on Twitter and recently joined Instagram.)

"I think what it is, is in this moment there's just so much social media, and that's why she's had more word of mouth than anybody," Alt says. "I mean, I like Kate. She's a pretty girl. But all the girls are nice and all the girls are pretty."

What do you think of Alt's comments?