Not as engaging as Rec series, not as interesting either. This is a quite frivolous dramatization of supposedly real (???) case happened in Madrid back in 1991.
There are some visually interesting scenes (the camera showing the “cross” between building parts or background people walking backwards were the most memorable), but overall it’s a pretty standard picture with your typical Hollywood cliches (“screamers”, ridiculous crawling scenes, etc.). The movie actually morphs into a parody on itself because of two very ridiculous scenes in the middle of it. I get that it’s a “homage” to old 60/70s movies, but it’s executed in a way which harms the movie and the atmosphere it built.
The score is nice (and of course it’s retrowave), but it’s just there and that’s it, entirely forgettable.