Our trip at Pere's apartment was absolutely wonderful. The flat is really nice - equipped with everything you need and very clean. We loved the modern interior. Check-in with Pere's sister was also really nice! She even went out of her way, so we could check-in 30min early :)
The flat is not located in the old town center of Valencia, but everything was quite easy to reach by foot (~15-20min walk to the old town through the bustling neighborhood of Russafa). Since we love to explore cities by wandering around, this was no problem for us and it was great that there was free parking around the house.
The only minor point was that the house is not really sound-proof, so it can be a bit noisy. But I guess, this is the norm in most Spanish buildings and it wasn't really that bad. I would definitely recommend Pere's apartment for a stay in Valencia!