At first glance, the waffle fry seems like a superfluous novelty. When a normal skinny French fry won't do, let's add holes to it! This is the same line of thinking that led us to assless chaps, people.
But surprisingly, adding holes to a potato before cooking it in oil actually serves a purpose: it allows it to cook faster and more thoroughly. By reducing the volume and increasing the surface area, the center of each part of the potato is reached faster by the heat, and since the waffle fry blade cuts its holes evenly, the fry itself is cooked more evenly. This also means the temperature of the oil can be reduced while still maintaining quality output, thereby saving energy.
Waffle fries aren't terribly common, but they are served at your area Chik Fil-A (closed on Sundays? Really?) if you'd like to see them in action. They're pretty great, crispy on the outside, moist and umami on the inside. They also hold a lot of ketchup / honey mustard / chili cheese, if that's your thing.
And now for an interesting story ...
The waffle fry itself has been around since the turn of the 20th century, but the process for making them was generally customized and convoluted. But when it finally got streamlined and went bigtime, it became the center of an important law case on confidential disclosures and the obviousness test of the United States patent system.
The first known waffle fry cutting machine was invented in early 1979 by one Edgar Matsler. He tried to sell his machine to Lamb-Weston, the world's largest producer and seller of potatoes (they have the McDonald's contract), but for some reason at his demonstration the produced fries were bad. Still, Lamb-Weston offered to license Matsler's technology and offered some R&D to improve it. Instead, Matsler took his product to J.R. Simplot (#2 in spuds) and signed on with them.
Fast forward to 1983. Lamb-Weston releases a new product called "CrissCut" - frozen waffle fries. And they offer up a patent for their process of making the waffle fries and then freezing them. "Whoa, whoa, whoa," said McCain Foods (frozen foods entrepreneurs). "You can't patent that. That's obvious. Look, there's a patent for making waffle fries (Matsler), and a patent for freezing fries (the Strong process)."
So they went to court, and Lamb-Weston made a very interesting and novel argument: because Matsler's invention was presented to them under a nondisclosure agreement, it wouldn't've been obvious to the common person that you could make frozen waffle fries. And the court responded with an even more novel rebuttal: well, sure, Matsler's machine isn't obvious, but what about the potatoes he actually cut? He had handed some out to McDonald's and Dairy Queen customers as part of his demonstration, hadn't he? Anybody could look at that waffle fry and figure it could be frozen, couldn't it? That's obvious. So they invalidated the patent.
(This argument was also novel because it allowed the court to avoid having to figure out if confidential disclosures constituted prior art for the purpose of invalidating a patent.)