Greko Greek Street Food executes the fast-casual Greek playbook competently. The gyros are properly built. The falafel is well-fried. The tzatziki is fresh. The operation runs efficiently and the price point is honest. None of this is in question.
What's also true: Nashville has a food scene that has raised the bar high enough that 'competently executed fast-casual' is a crowded category. Greko isn't doing anything that distinguishes it from a dozen similar operations in other cities, and it isn't trying to. The food is interchangeable with every other respectable fast-casual Mediterranean concept.
The gyros and falafel are solid. The operation runs efficiently. Nothing here is bad, which is different from anything here being worth seeking out.
Greko is a fast-casual Greek street food restaurant doing the format competently. Properly built gyros, well-fried falafel, fresh tzatziki, efficient operation. In a city with more interesting options, being correct isn't a sufficient recommendation.