Overall for the price it was very good for three friends for a weekend.
Good: the double bed, cleanliness, location in the middle of Sevilla with a little plaza close to with nice breakfast and lots of people and possibilities to get a drink or party. Well functioning bathroom and kitchen, making it possible to cook a little and wash your clothes. Good wifi, tv, and feels like a safe street/neighborhood.
Bad or could be better: if you plan on being more than two, there is a sofa/bed which is not that good and a little broken and only has very thin linnets and no duvet. The bathroom smells of the sewer, one of the curtains couldn't be dragged down, there are two small balconies which is nice, but the doors to it cannot be locked (otherwise we are just stupid and don't know how), and in the weekend there were a lot of people right outside partying a being really loud, so if you are a light sleeper you would probably need some earplugs. We also had a bit of a problem finding they box with the key and the exact apartment but it all worked out fine.
As stated at the beginning, a really fine apartment in close to everything in Sevilla, and especially good if you are only one or two persons. We didn't need any help but Sebastian and Ricardo got back to us quickly and communicated well. We are studying Spanish here in Spain so we wrote in Spanish to them where the communication was good and clear, but I cannot speak for foreigners who don't speak Spanish. Thanks for the stay, Sebastian and Ricardo.