That synopsis is slightly more innocent than the truth of the story's subject matter. Same with Lili the main character. Riverón places her in a much darker, ambiguous position. The film is slow, depressive and methodical with damaged characters going through some disturbing situations.
The cast give excellent performances bringing this flawed and scarred family to life. They all seem to be zombie walking through their existence. It creates a haunting atmosphere that is relentless in the way it grips you. The slow pace can at moments become annoying and there are moments when it could have benefited from a little speed. Still I get what the director was going for.
Most of the film's horror is subjective, really playing on the psychological nature of the story's material. The overall nature of these characters relationships create an atmosphere of tension and danger. The soundtrack adds an unnerving edge. This isn't a shock horror or heavy thriller with jump scares. Everything is minimal, except the cruelty on display. Plus asthetically, the look and feel of the film pulls heavy from traditional horror, both in setting and character.
Overall "Is That You?" is a nice psychological horror for indie fans looking into dark character study films that use atmosphere to frame people's darker sides. If you go in thinking this is a gory, thriller then you will be disappointed. This film goes deeper than that, and in a slow, disturbing way. I say check it out.