Perfectly serviceable monster movie. Sean Cunningham delivers exactly what you want, with just enough gore and bad ends for people.

As far as 80's horror goes this one isn't too bad. It's got some very memorable deaths, especially the one immortalized on the movie poster. The trademark "non-monster but detriment to the team" is actually half believable instead of just literally terrible at absolutely everything (though let's be honest he is pretty terrible at almost everything). Even so, for a low budget horror flick that feels like Alien-except-under-the-sea it manages to entertain.