Delivered as promised. Marta is a very professional host. I would like to point out that, during the winter months, Sevilla is rather cold - at least at night and in the morning. You totally need heating during that period (a fact which many unfortunately deny or ignore). Marta's apartment has two air-conditioning devices which can be set to heating. Since there are two rooms without these devices, she provided mobile heating units for these rooms; this showed us that she paid attention to her guests' needs. We also enjoyed the bathroom and the modern and functional shower. Everything else was in order.
The apartment is also quiet and the location is, as pointed out, great. Obviously, when there is a Sevilla home game, things can get noisy, but these games do not happen so often and when they do, usually end before you go to sleep.
Possible downsides? As has been mentioned, third floor no elevator. That, however, did not bother us a lot (we have three little children, one 15-month-old), but do bring a small pram since the stairways are a bit narrow. After all, walking stairs is healthy. Other than that, which is very minor, an excellent opportunity and highly recommendable. Well done!