I have spent one full month in Marcelo's apartment. It is extremely well located, as it is between the beautiful Turia park and the beginning of the city center. You get everywhere in no time with a short walk.
There is a big Consum supermarket nearby which was best for me for regular grocery shopping.
The apartment is equipped with everything you need and cooking is no problem even though the kitchen counter is a bit small due to the small apartment. There are two one person guest couches which can be unfolded to a full size bed. The internet/wifi is 500mbit up and down, which is extremly fast and reliable.
Two downsides to the apartment are the windows and lighting. The windows are not sealed at all so it does get a bit loud in the morning hours and evenings. And the apartment has two windows but they are facing another apartment so there is no sunlight coming in. You have to have the lights on mostly.
Marcelo and Noelia were always quick to reply and helpful. The neighborhood is safe and Valencia is a beautiful city. Thanks for everything.