I have an aprtment about 120 km north to Castellon and go to Castellon once or twice per year for shopping. This summer I stopped on the wa to see Oropesa del Mar, specifically Marina d’Or, as I have only seen it from a distance before.
The place is filled with high store buildings, many of them unoccupied. Early July the place was not deserted but there were not many people around. Also I felt the place had no real life like a “normal” Spanish village. Very few cafés etc…
To each his own, but Marina d’Or is definitely not in my taste.
I also think renting will be difficult due an enormous glut of apartments there.