Having walked from Cádiz to Seville over the last two weeks, I plan to do an English translation (of sorts) of the Spanish Via Augusta (Cádiz to Sevilla) guide, with my notes added, for anyone who is interested. I will post information here once it is done, hopefully within a week or two.
There was only one section that I would not do again, and that was from Las Cabezas de San Juan to Utrera - over 31km of dead boring, hard surfaced walking with not a single village or interesting small farms to at least provide your mind with a break. Also almost no shade (except for the odd overpass) and no water.
El Puerto, Jerez and Lebrija were the highlights for me.
I am in no hurry, so have been taking it easy with a few 'short' days of only around 15km. I covered Cádiz to Sevilla in 9 days walking, with a rest day in Jerez and 3 days in Sevilla. I actually stayed in Alcalá just before Sevilla as everything was either full or madly overpriced because of Semana Santa - Holy Week, and caught the bus (€1.65 each way, around 25 minutes) into Sevilla to visit. This also made it possible for me to walk the Alcalá to Sevilla section without my backpack - what a pleasure!