I have had squab one time, when my cousin in New York City invited us all to an upscale restaurant before going to the theater. I'd have to say it does taste a lot like duck, but it also had some of the same qualities as a really savory turkey. There wasn't a lot of meat on the plate, but it was very rich and satisfying. I'd definitely order it again if I ever saw squab on a menu.
When I got back home from NYC, I went to my favorite grocery store's meat department and asked a butcher where to buy squab locally. He said they used to order squab during the Thanksgiving/Christmas season, but they didn't sell enough to make it worth the investment. People just don't like the idea of eating pigeons, even though squabs are nothing like street pigeons.
It's a tough sell, unless the customer is already familiar with the product and knows how to prepare it properly.