The makers of the movie say the ship is 725 meters long. They're the people who designed, modelled and detailed it. Who put it in the virtual environments. Yes, there was some camera trickery (the Enterprise was made much smaller to fit over the shipyard location - just as Kirk running into the ice cave on Delta Vega was a child running into a half-sized cave entrance), but 725m is their stated intention. It's ridiculous
that some fans seem to think they know better. Who are you guys kidding?