I recommend this place for several reasons, but most importantly, for the host! RIKi is a good guy, very polite and always willing to help. my stay felt comfortable and safe. I wish him the best!
I also recommend this place if you're going to the congress hall. It's just 10 min by foot.
If you're just visiting Valencia. I would rather stay here or in this part of the city. Public transportation is close by. Price wise it's more affordable. And the apartment is in a good location. It's safe. You wouldn't worry about going home late at night.