Paul Luna, best known for teaching Atlanta to love tapas in the 1990s, operates his latest place with the sensibility of a culinary activist. He chose its location in a dreary stretch of Downtown in part for the low rent; in turn he charges the lowest possible prices for his small plates. Although I enjoy two warmly spiced, braised chicken legs for $3.45, or garlicky sauteed shrimp for $4.15, I sometimes crave the more complex cooking that’s currently absent from Luna’s menu devoted entirely to small plates. But I admire his mission to feed people affordably and well, and the restaurant clearly has an appreciative audience: His all-you-can-eat Sunday pasta and risotto feasts, for $9.95 per person, often sell out. The bohemian dining room—mismatched chairs and art, low-slung sofas, sections of the ceiling painted in groovy patterns—boosts the appeal.