The first half of the movie really isn't bad. You are absolutely correct that is turned into a lot of nonsense once Pinhead got loose.

I am not a fan. I just happen to enjoy movies. Fans are embarrassing.

I hate how they made Pinhead into a generic slasher villain, he worked way better when he was a side character.
Horror_Metal

The "Hell on Earth" aspect could have been handled more gracefully and in a way true to the spirit of the cenobites. To me, Pinhead's aspirations sounded grander than merely killing lots of people in gimmicky ways. Maybe he should have formed some sort of sadomasochistic cult.