We stayed at Raul's Sun Studio for nearly an entire month this summer.
Raul was a great host and provided everything we needed for our long stay.
The apartment is exactly like it appears in the pictures on AirBNB. The space is very clean and all appliances worked perfectly.
The location is about as good as you can possible get when you are staying in El Carmen - near Plaza Reina, La Lonja, and the Mercado. In addition, it is only a short walk to the Ruzafa neighborhood which has a less touristy vibe for late night strolling and eating.
The studio is also very quite - the restaurants in the same alley way as the apartment are busy from around 2PM until 10PM, but cannot be heard from the studio. You occasionally hear some footsteps and talking from the other apartments in the same building, but nothing that is too bothersome.
We had a tiny snag on check-in - the cab driver took us to the wrong street. Once we found the correct street (next street over) it was easy to communicate with Raul via the AirBnb App (or WhatsApp) in order to get into the studio.
We wouldn't hesitate to book Sun Studio on our next trip to Valencia.