Its nice to see Nicolas Cage in a film deserving of his talents.
Arcadian is not an exceptional horror thriller but what it does do, is done competently enough to be deserving of praise. It has a serviceable story, that reminds me a little of "A Quiet Place" from 2018. The core premise is not quite the same but the monster effects are similar, as is the rural setting.
The tension is ratcheted up nicely as the story progresses. As is always the case with what is essentially a survivalist horror, we know the creatures are going to get in but what happens next is, of course, the interesting part. Along the way we get to know the key characters, including Cages father figure. His effective absence part way through film and his return near the end, is a little disappointing but given this film has a coming of age component, its understandable.
Acting is decent throughout and you can certainly relate to the plight of Cages little ad-hoc family. The creature effects work well enough too but somehow, they are just not all that creepy or especially menacing. This tends to rob the film of a real post apocalyptic horror vibe. I think revealing exactly what they are, early on, was a mistake too that took away any reveal/jump scare potential, from the film.
All that said, Arcadian is in most respects a worthwhile watch that you should consider adding to your horror/thriller inventory. Definitely worth a look.