We stayed for 5 nights in August (2 adults, one 6 year old). The location is good for the beach (about a 5-10 minute walk away). There are a couple of supermarkets and some nice places for breakfast, lunch etc near to the flat. There are buses and metros nearby to get into the centre of Valencia.
The flat itself was clean but a bit worn and would benefit from a bit of maintenence. The beds are comfortable and the shower had plenty of hot water, which was great after the beach. Also the washing machine and dishwasher came in handy. The living room has air con, which was necessary during our stay but the bedrooms only have ceiling fans/standing fans, so they were a bit hot.
I had a couple od niggles, I.e the kettle leaked everywhere, the plug in the bathroom sink didn't close, the kitchen tap was lose, as were some pan handles. However, overall it's a good sized and comfortable flat at a reasonable price.