Arun George’s review published on Letterboxd:
What makes 'Gon-ji-am' worth checking out is probably the fact that a place such as this really exists. Plus, most actors have used their real names and portray themselves in the film (adding to its 'authenticity' factor). So, when some of them eventually die in the film (hell no, that ain't a spoiler!), you get a feeling that they could really be dead (à la 'Cannibal Holocaust' and later, 'The Blair Witch Project', and many more).
The 'live-stream' aspect does lend some real-time tension to the film. The cameras, thankfully, aren't too shaky (like in most POV horror flicks) and there are some added technological twists (like the drone!) which aren't fully explored. Yet, the writing and the horror itself is so derivative that you can clearly predict what's going to happen (if you've seen 'The Blair Witch Project', 'REC', 'Paranormal Activity' 'The Tunnel', or 'Grave Encounters' or similar films).
That indeed is the biggest bummer! 'Gonji-am' probably came out, maybe, a little too late. If you haven't explored the found-footage genre much, this could intrigue you to a fair extent. There are jump-scares but Director Jung Bum-shik struggles to sustain the horror throughout the film. The actors are not-bad choices. Some of them manage to convey the dread really well.
I watched this by myself on a cold, rainy night and honestly, it left me a little disappointed. Nonetheless, you can give it a watch if you like the genre and horror-films in general!