I was in Seville for a Spanish course and I stayed in Marta's place for six weeks and so could get to live this studio-apartment to the full. It is a great place to stay in Seville, it's very central but still very quite.
The apartment is situated on a ground floor overlooking the patio so the only noise you might get is when other people who live there pass by, but there's no noise from the street.
Facing the patio also means that there is not much daylight coming in. That might be a bit of the problem in the wintertime, but I believe that's an ideal situation during hot Sevillian summers. However, the illumination in the flat is great so for me it was really not a problem. I had to pass many hours working on my computer and felt very comfortable there + the tv screen can be used as a second display.
The kitchen is well equipped, the shower and the washing machine work great. There is a very convenient roof terrace and on a sunny day your clothes will get dried in a couple of hours.
Should I again come to Seville for a language course, I would definitely change the school, but would again stay in Marta's apartment.