Maniac is a psychological thriller and science fiction film directed by William Lustig in 1980. It tells the disturbing tale of a deeply troubled man whose traumatic past spirals him into a world of violence and madness. The film famously evokes both revulsion and empathy among audiences with its excruciatingly realistic portrayal of the deranged mind of its protagonist, who oscillates between moments of chilling savagery and deep remorse.

Frank Zito, played by actor Joe Spinell, who also co-wrote the screenplay, is the eponymous maniac at the core of the film. Frank's character is introduced as an everyday guy residing in New York City. Still, the fact that he is deeply scarred by a brutal childhood becomes apparent as the narrative unfolds. Frank has transformed his traumatic experiences into a twisted obsession with mannequins which he considers as his friends, companions, and victims.

Struggling with his past, Frank becomes entwined in an intricate web of gruesome fantasies. Despite his troubled persona, he manages to strike up a friendship with a talented photographer named Anna, played by Caroline Munro. This unusual relationship serves as an intriguing juxtaposition to Frank’s incipient madness. As the story progresses, the audience is taken on a nerve-wracking journey, witnessing Frank's descent from a man wrestling with his inner demons into the depth of psychopathy.

Director William Lustig manages to skilfully humanize Frank’s character, highlighting the tragically severe impact of child abuse, a subject that was mostly avoided in mainstream media at the time. The storytelling in Maniac is simultaneously repulsive and magnetic, making it a movie that is hard to forget.

Shot mostly at night, and set against the gritty backdrop of late 70s-early 80s New York, ‘Maniac’ is both a grim reflection of the city's darker side and a character study of a psychopath. The grimy setting perfectly complements the storyline, adding to the chilling aura of the film.

Throughout the film, Lustig does not shy away from vividly graphic imagery to amplify the disturbing nature of Frank's barbarous acts. The makeup effects, delivered by renowned artist Tom Savini, are alarmingly realistic and stark. The shocking spectacles of violence serve as hard-hitting reminders of Frank's de-evolution, pushing the boundaries of the slasher genre of its time.

The film remarkably juxtaposes these disturbing visuals with a haunting musical score; the eerie tunes pulling you further into Frank's twisted world. The sound design is eclectic and atmospheric, helping to build the tension and horror that permeate the screen.

One of the most notable aspects of Maniac is Joe Spinell's outstanding portrayal of Frank Zito. He delivers a highly nuanced performance that conveys both the absolute terror instilled by his character and the pervasive sadness that emanates from his tragically doomed existence. Spinell's chilling performance, combined with Munro's unsuspecting victim role, creates a contrasting dynamic that further emphasizes the terrifying unpredictability of this film.

In conclusion, Maniac, despite its initial controversy and mixed reception due to its violent and grim portrayal of a serial killer, has since achieved cult classic status. The film has carved a niche for itself in the pantheon of horror cinema for its unflinching portrayal of the chilling Freudian journey into the mind of a disturbed individual, its visceral visuals, and its psychologically complex plot.

Its strength ultimately resides in Lustig’s austere direction, Savini's gruesome makeup effects, and importantly, Spinell's terrifyingly real performance of a serial killer on the run from his past. Its influence on the horror and thriller genre remains evident, with its themes and narrative still resonating with many filmmakers today. Maniac offers more than just a tale of terror; it provides a thought-provoking study on the human psyche's darker facets and the devastating consequences of untreated mental health issues.

While the film is unquestionably not for the faint-hearted, for those who appreciate a well-crafted psychological thriller, Maniac offers an immersive, albeit harrowing, viewing experience. The film's disconcerting nature ensures it continues to unsettle audiences to this day, making it a must-watch for anybody interested in unorthodox depictions of horror.