We stayed at Melanie's apartment for a week. It was in a perfect location - from the airport we just jumped on the metro line straight to Maritim, took about 30 mins and cost €5.90 single fare. The apartment was about 5 min walk from the metro station and 2 mins from a tram stop.
We arrived a little early to check in but communication with Melanie beforehand was great and we met Angelica at the flat to get the keys. We also got a lot of really useful recommendations before we arrived for places to eat, bike hire and supermarkets nearby which was great.
The flat is in a residential area about 5-10 mins from the port and fabulous beach. There is a large Consum supermarket just around the corner where we stocked up with water, snacks, etc. We did have a couple of evenings where we ate outside on the terrace which was lovely, followed by a late evening walk along the beach.
We walked about 20 mins to the science park and also got the metro into the old town most days. We found it best to get a Suma 10 ticket for €6.60 (zone A) which gave us 10 journeys on metro, tram or bus (although we only used the metro while we were there)
My first visit to Valencia and it was well worth hiring a bike for a day - the cycle paths are fantastic and really safe.
The apartment was great for my husband and I. The bathroom is off the main bedroom so if you have more people they would have to go through the bedroom to get to the bathroom.
As this is a residential block, midweek you will hear noise from neighbours going about their everyday business from fairly early (we were woken a couple of times by an alarm going off at 7am). You can also hear the bells ringing from around 8am so if you want to lie in then ear plugs would be recommended.
We did explore a fair bit of Valencia mainly by foot and the location of this apartment was ideal for us. Wouldn't hesitate to recommend and hopefully we'll be back in the not too distant future.