We have stayed in Seville many times in all areas of the city.
Opera is by far our favourite, the location is great, Mercato di Feria ( amazing food ) at the corner, Hercules bar opposite which is a great hangout and a short walk to Hercules for nightlife.
The apartments are simple, clean and even have a small rooftop pool..it was perfect for us..the rooms are small, but we didn't come to Seville to hang out in our room.
Definitely coming again.