Firstly the communication from Carles was perfect. He helped before and during the stay. We loved the location of the apartment as it is so close to most of the places you would want to eat and drink. The flat itself also is very nice and has all of what you need (also had Netflix which was a nice touch).
We would say though (and Carles did tell us upon arrival) - that there is contraction Work going on right across from the stay. So the noise level from say 8am approximately throughout the day is more than usual. He did give us earplugs too though. But of course we were out exploring for most of the day anyway.
We closed the windows in the flat when we went out. But when arriving back noticing a slight smell inside, which was coming from the Kitchen sink (maybe the drains?). It went away very quickly after opening the windows for a few minutes though.
Overall a good place to stay in Valencia, with a host is more than willing to go out of his way to help you enjoy your time!