It's similar to the hype behind In-N-Out and Chick-Fil-A
The food itself is decent at best (especially the Cane's sauce & Texas Toast. The chicken is moist & big, but bland/unseasoned). However, the service is always top tier (including being extremely fast), the food is always hot/fresh and it's reasonably priced.
Interestingly enough, we just got Saavy Sliders down here. They already opened 1 location each in Dallas & San Antonio with fairly big expansion plans in the work. They have good Cajun Fries, but otherwise, that's the place that I don't get the hype over. It's overpriced and the service is poor on top of having mediocre food.