The premise is not original, but something that could be a good watch if done well.
This was not done well.
The pacing was totally off - nothing happens for a long time, and this setup does nothing to add to the suspense. When things start happening, it goes too quickly. The viewer doesn't have time to develop a sense of fear or suspense.
The acting is mediocre, with mostly cliched characters. The main female character (the bookish younger sister) shows very little emotion, even during a couple of the obvious "scary" scenes. I could tell where I was supposed to feel scared, but never actually anything near scared.
The creature makeup is a mess - looks decent in dark lighting, but when the creature is better lit, it looks very amateurish.
And, what I think were meant to be the movie's "plot twist/insightful lesson" near the end was just a muddled mush of confusing ideas. The writers were trying to make a profound point, and just ended up making a profound mess.
I stuck through the movie because I'm stubborn, but I actually couldn't wait for it to end. Don't feel obligated to watch this movie to the end - it does not get interesting, it does not get better, it does not redeem itself.