Javi's apartment was perfect for our family of 4 - it was spacious, very clean, with a modern feel, and a great location a quick 15-minute walk from the Santa Justa train station, and about the same to the Cathedral, at the heart of the city. Plus, the terrace was a huge added bonus for us, as we were able to have breakfast there (with a view!) and chill with a glass of wine at the end of the afternoon.
There were plenty of great restaurants on the same street, and Javi's friend who checked us in provided some cool recommendations for places to eat in the neighborhood. They were especially flexible with checkout time, which proved really useful to me as I had a train late in the afternoon.
The street the apartment is in can get quite noisy at night so I'd recommend bringing some earplugs if you're a light sleeper - other than that, I would absolutely recommend Javi's place for a great stay in Seville!