At this Greenwich "hole-in-the-wall" (and its larger full-service, sit-down sibling), the "succulent" build-your-own burgers "nicely served" on toasted bread "will leave you with a big, fat, greasy smile"; "seating is limited" in the original location's "closet-size" space, but "what it lacks in ambiance" it makes up for with "friendly" service and "16-napkin", "finger-lickin' deliciousness"...