As long as you mean regular, and not the oversize "$6" version, I'd agree, it's both one of the more distinctive thing on their regular menu, and pretty tasty for a fast food burger.

Their basic burgers seem distressingly interchangeable with Jack in the Box; I'm not super-fond of either. But my wife grew up with Carl's, and we go occasionally.

Carl's/Hardee's has made a thing of trying for the most outrageous and unhealthy dishes; AFAICT, they don't sell that many of them compared to the regular menu, but the publicity brings people in.

OTOH, some people probably DO get them just to be extreme, even if not regularly - I'm reminded of one trip through LAX when out of desperation I went to the in-terminal Burger King. Adjacent to me in line were a couple of very young (18-21ish) guys with commonwealth (probably Australian?) accents, and I nearly burst out laughing when one said something along the lines of "We're in America now. I've GOT to get a triple Whopper."