Location and the looks of the apartment are perfect. You can walk to the apartment within 10 minutes from the Metro and when you leave the buidling you are in the middle of the old town. We rented a bike, and in 15 minutes we were at the beach. (lights of the bikes got stolen in front of the building unfortunately, but you can't place them inside somewhere).
However, if you are 1.80m (as I), the ceilings are really low, so be carefull! Next to that, during the booking process, Gloria told us we could stay in the apartment until 2pm (which we requested because of flights), but uopon arrival her son told us we had to leave at 12pm, because of new guests coming in that day. After an emailconversation they told they do could offer to leave our lugguage in the apartment until 2pm, so thay could clean. We choose not to do this.
Besides the apartment being low, it was also quite noisy. We could hear the next door neighbours going to the toilet at night, in detail... Also, maybe because of the thick walls, the wifi only works in the living area. Not that you need wifi in the bedroom on your weekend getaway, but yeah, no searching for a breakfast spot online out of bed ;-)
The worst was the bathroom. It looks great, and the shower is quite nice, but the boiler started leaking quite severly while taking a shower. This made there was JUST enough water to get 2 hot showers, but after that the floor was wet, even in the hallway. They provided us with 4 towels, but we had to use them for the floors. There were a lot of small bugs in the bathroom, I guess because of the water.
The city of Valencia is beautiful and there are a lot of nice places to eat around the building, even as a 24/7 shop with water, beers and some other utilities. The Central Market is beautiful and we had a lot of nice things to eat there too. It's almost around the corner!