I can't say enough positive things about my time at this rental. I spent a month in Seville and would happily use the place again. It has everything you need to live comfortably (dishwasher, washing machine, A/C, fast wi-fi [for anyone who needs to work remotely], etc.), either for a short trip, or for an extended stay.
The location is super central, but far enough removed that you don't have any noise pollution during the bustling nights. There's a grocery store, an excellent coffee shop (Virgin Coffee), and the Setas de Sevilla just a couple minutes away by foot. The shops (Zara, H&M, El Corte Inglés, etc.) are also maybe a 5- to 7-minute walk. If you're planning on taking any day trips from Sevilla-Santa Justa, you could also easily walk to the station in ~20 minutes.
The hosts were very responsive and accommodating. At one point, the electricity in the building went out and Alfonso kindly kept me updated. I also requested a later check-out time, which was generously allowed.
As far as any flaws go, there really aren't many. Off the top of my head, there are only three sets of windows in the rental and I kept the shutters closed on two of them for privacy reasons. One overlooked the small back patio of another building resident and the other set looked out onto the bike storage area where anyone could see directly back into the apartment. This didn't bother me much, though.
There's also the fact that the rental is on the ground floor, which is excellent if you have a lot of luggage that you don't want to be lugging up stairs, but it also means you're close to the front entryway, so you can hear every time someone comes and goes. On the whole, though, most residents were quiet and respectful.
There's also the perk of it being considerably cooler on the ground floor than when you get even one or two floors up. I didn't have to keep the A/C running continuously as a result, even in the hot August days.
Overall, I loved this rental, and the fabulous design really turned an otherwise small space into a very functional and comfortable living area. I'll definitely be back on my future visits to Seville!