I last had lamb liver at The Parthenon about a year ago. They have a "mixed grill" mezes plate consisting of lamb liver, lamb sweetbreads, sausage, and meatballs. The flavor of the grilled liver was quite strong--more livery than lamby--but pretty good. You do have to be a liver fan to enjoy it though. The star of the plate was the house-made sausage, nicely spiced and heavy on the orange rind. After dinner our waiter asked how we had enjoyed the liver. It was obviously a favorite of his and when not everyone at the table expressed unreserved enthusiasm he seemed slightly offended and began extolling its virtues, at one point pulling out his pen to make an anatomical drawing of a lamb liver. Very amusing.
So, if you're a hepatophile, I bet you'd be thrilled with lamb liver. The stuff at Green City Market is probably really good, at least as liver goes. Let us know how it was.