Making a good Extra Anejo is difficult. It is a category, where the products are usually expensive and expectations are high. Extra Anejos are almost exclusively used as sippers and that gives a high focus on smoothness, sweetness and depth of flavor/aroma.
That said, La Serpiente Emplumada Extra Anejo is a well made version of the extra anejo category. The colours is amber and deep. The viscosity is oily and the flavor profile is round and mellow with rich notes of butterscotch and vanilla.