There's two Blue Marlin restaurants - one in the marina and one far south along the beach. Obviously the beach one is the choice provided you are happy to transport yourselves out there.
Once there you are met with lots of tables of high-society guests squeezed together, reflective prices of food and drinks, a couple of models doing catwalks down up and down past the tables, a dancefloor/music area with dj and canopy, and a lovely rock beach area where others lie and drink. Not a bad place if you have the $.
The special whole fish was €90/kg - so 1.2kg semi-reasonably fed 5 of us. But really it was only because there was extra plates of squid (dishes were about €20-40 each even for a starter), nibbles, and because I asked for the fish head, fins and skin because otherwise they would waste it.
I'm happy to have experienced it once (similar to Nikki Beach) but my bank balance doesn't fit in there. If you do go, make sure it is for more than just a meal. Enjoy the beach and music paradise.