Cadiz is the dirtier version of Seville that also lacks the stellar individual attractions. For sure, its good fun to get lost in amongst what is supposed to be Europe’s oldest city streets and to look out at the beaches and lighthouses from the sea wall views, but Andalusia has some true gems that should rank above Cadiz in priority for your trip.
If do go though (he writes after scathingly criticising the place!), it’s a pleasant afternoon getting lost walking through the Old City, having some sherry overlooking the Plaza de San Juan de Dios and checking out the beaches at the far west end of the Peninsular.