This series has polarised viewers. Either you like it or you won't.
I really liked it. In fact I watched the last 20 minutes of episode 6 again.
It's not a monster genre show, but like another reviewer said, it's sociological commentary. The monsters are just there to provoke thought: are they a punishment from God for sinners, or are they just a supernatural phenomenon?
Viewers have said there are plotholes and dropped plotlines. Spoiler here: for example, no follow-up to the detective and his daughter. Actually, it can be inferred that he chose to protect his daughter by not exposing the chairman, and this paved the way for the New Truth and the Arrowhead to flourish. End spoiler. Throughout the show, there is sufficient information for you to make inferences and draw your own conclusions.
The last episode sets the scene for a second season. Hence the cliffhanger.
Anyway, if you enjoyed series like Stranger and School Nurse Files, which aren't so mainstream, chances are you'll like Hellbound. I preferred Hellbound to Squid Game and Sweet Home which are more populist dystopian. Hellbound is smarter and more unique.