Qdoba was founded in 1995 when Colorado native Anthony Miller and partner Robert Hauser opened the first restaurant in Denver. It was so successful (over $1.5 million in revenue the first year) that it spawned a chain. Now there are over 350 restaurants across the United States. In 2003 it was acquired by Jack in the Box.
Qdoba serves San Francisco style burritos (large foil-wrapped burritos), tacos, nachos, quesadillas, taco salads, Mexican gumbo, and guacamole that's made fresh every day on-site. It's like Subway for Mexican food: most menu items are prepared fresh right before your eyes across the counter as you tell the employees what exactly you want on them. For instance, when they are preparing a burrito for you, you select the type of beans, salsa, and other toppings.
The burritos (especially the queso burrito, my biggest recommendation) and nachos are exceedingly tasty and fill you up nicely. You won't leave hungry unless you have a ginormous stomach, even after having only ordered one item (before my first trip I thought "Can I get something with the burrito??"). My only criticisms are that the chips can sometimes be too salty and, and this is just me, I like variety when I'm eating and I really wish it was a little more like Taco Bell where you can order three to five different things and still have room for dessert. Or maybe Qdoba could have meals ala Panera Bread where you could get something like a half burrito and half nachos/taco salad/quesadilla.
Speaking of Panera Bread, Qdoba was recently involved in an interesting lawsuit in which Panera attempted to invoke a clause in their contract with the White City Shopping Center in Shrewsbury, Massachusetts that provided that Panera would be the only sandwich shop in the center. This was an attempt to block an opening of a Qdoba nearby. The argument was that burritos and other tortilla-based foods were sandwiches. Superior Court Judge Jeffrey Locke disagreed: He said "A sandwich is not commonly understood to include burritos, tacos and quesadillas, which are typically made with a single tortilla and stuffed with a choice filling of meat, rice, and beans."