Sector 7 is at best a routine Alien copy. It takes far too long to get going. The monster does not turn up until 47 minutes into the film, which is taken up by the not terribly interesting dramas between the one-dimensionally sketched characters. Even then the dramatics never go beyond the usual company skulduggery and the group skulking around the corridors trying to avoid/trap the monster. When it is not churning cliches, the screenplay is vague and does little to explain exactly what the monster is and how it relates to the shoals of glowing fish that we see in the prologue, or how we go from the single fish that is brought up from the depths and infects one of the crew to become a full-blown monster.
The film does however pick up with the introduction of the monster, which is brought to life with some imaginative CGI effects. Here Sector 7 mounts to a decent all-out climax with Ha Ji-won up against it in hand-to-hand combat. Director Ji-hoon Kim manages to get in some fine scenes with Ha Ji-won being pursued across the rig by the monster while on a motorcycle; it leaping off the edge of the platform to catch Oh Ji-Do in its jaws; of Ha Ji-won setting it on fire and battering it with a wrench; and she taking a giant leap off a crane as the creature follows, before she catches a pole to swing around so that it misses her by inches. Still it is not enough to make Sector 7 anything more than a routine film at best, a modernised version of The Relic set on an oil rig.
Sector 7 was released to Korean theatres in the 3D process. This unfortunately becomes a millstone that drags it down. The opening scenes as we are introduced to the rig and crew has things falling, coming into camera and so forth, as well as an absurdly gratuitous motorcycle chase across the rig with bikes jumping in slow-motion, for no real reason other than to show off the 3D. Alas when seen flat, these only make for contrived dramatics.