(USA TODAY) It's game on for the pretzel burger. Today Wendy's begins its national roll-out of the long-awaited Wendy's Pretzel Bacon Cheeseburger, a $4.69 premium burger served on a toasted pretzel bun. In about two weeks, the burgers should be available coast to coast. The long-awaited burger is made with warm cheddar cheese sauce, thick-sliced bacon, lettuce, tomatoes, red onion, smoky honey mustard -- all stuffed between a pretzel bun. Wendy's is counting on the pretzel burger being a fast-food game changer. None of the major national burger chains currently sell a burger in a pretzel bun. The move not only separates Wendy's from the competition, but rekindles hazy memories of Wendy's as an industry leader in fast-food innovation. "This is the most anticipated new product in recent history," said Craig Bahner, Wendy's chief marketing officer. Even then, the initial roll-out is as a limited time-only product that will be available through the summer. Christopher Muller, fast-food guru and professor of hospitality at Boston University's School of Hospitality Administration, calls the new product a "very, very big deal." The pretzel buns are artisan baked - much like the soft pretzels commonly sold at the mall. The top of the bun is hand cut prior to baking, giving each pretzel bun a unique appearance. But the burger comes packed with 680 calories and 1,110 milligrams of sodium. (By comparison, a Big Mac at McDonald's has 550 calories and 970 milligrams of sodium.) "When many fast food companies are attempting to acknowledge the problems of eating too many calories, too much white flour, too much poor-quality meat and too much sodium - bang - here we have the too much burger from Wendy's," says Cynthia Lair, assistant professor of nutrition at Bastyr University near Seattle. "Stick with those burgers that don't blow your whole sodium-carbohydrate-fat count for the day with one gut-wrenching burger." Wendy's won't say right now, but the product is likely to be considered as an addition to chain's permanent menu if it's a big hit nationally. Pretzel Burger