This is the ultimate grocery store, carrying every kind of food you could ever want, but selling mostly organic, imported, and specialty foods. Here you can find French cheeses, vegetables still on the stem, soft drinks from all over the world, and more fun things like that. They have a large selection of pre-prepared foods like cakes and other pastries, as well as a wide variety of wines. A restaurant is available in case you get hungry while you shop.
Of course, the big drawback is that none of this comes without a cost, and groceries here are fairly expensive. I would strongly recommend this store if you desire ingredients hard to find in standard grocery stores, and as far as "ethnic" foods go I would try ethnic markets first. Still, this is a great place to have it all at once, and it's a lot of fun to shop in.