After a "soft" opening on Saturday, the newest addition to the Shake Shack dynasty opened its doors on West 44th Street and 8th Ave at 11:00 a.m. today. There was neither pomp nor fanfare for the lunch hour opening, presumably because the Shack people knew they didn't need it. The long line, so closely associated with what one patient New Yorker called "Shack Culture," curled around the corner on 44th Street within a half-hour of opening.

The all-glass front and industrial-chic interior decor boast a Shake Shack that has evolved quite a bit from its early days in Madison Square Park. Culinary Manager Mark Rosati says they've learned a lot since, and are working with a larger kitchen and more efficient burger-piling processes that will cut down on the wait time for this location, which he expects to be the busiest of the five. The tables are the most interesting non-edible item, made by Brooklyn-based Counter Evolution, who ripped the enormous planks out of an old Chicago bowling alley. The zany light fixtures are I-beams bent into trapezoids, shaped to match the footprint of the only Shack-shaped location in Madison Square Park.

Though they have yet to begin serving wine and beer, their site-specific Concretes seemed to be satiating the lunchtime crowd. Some are a little overwhelming, with the "Jelly's Last Donut" concrete containing Doughnut Plant donuts, strawberry preserves and cinnamon sugar. One woman tried it and quickly pushed it aside, mumbling "Holy cow. That's just too much." (We have to agree.) But a seven-year-old articulated exactly how we felt about marshmallow and crisped rice "Great White Way" concrete, calling it the "best rice crispy treat ever." All concretes and shakes are made with frozen custard, the more egg-rich cousin of ice cream, explained by the Shack people as "when ice cream shacks up with soft serve."

But one vocal critic was found among the happily gorging patrons: Tanya Larzetti, 62, who sat with a can of diet ginger ale, tapping people on the shoulder to remind them that they were eating "Cholesterol. Animals. Very bad for you." She was later silenced by her enjoyment of a 'Shroom Burger, the ridiculously delicious deep-fried cheddar-muenster-portobello conglomeration that has satiated many a Shack-going vegetarian.

The Theater District location will be open daily 11 a.m. to midnight, but we were told closing time will probably be pushed into the wee hours to accommodate the area's late-night demands. Next up is an Upper East Side location on 86th and Lexington, set to open in a few weeks. And if you're down in Florida this summer and need your fix, we're told the Miami Beach location, which opened last month, has already begun cultivating a following of ex-New Yorkers who are teaching the Sunshine State how to wait on line.