Udhayam NH4 presents a gripping story that combines romance and thriller elements effectively. The screenplay is taut, with a strong emphasis on the chase and the obstacles the protagonists face, which keeps the pacing brisk, especially in the second half. The first half sets up the characters and their motivations well, though it leans more on establishing the socio-political context and the romance. The second half picks up momentum with heightened tension and action sequences that maintain audience engagement.

The film's music by G. V. Prakash Kumar complements the narrative well, with songs that blend into the story without disrupting the flow. The background score enhances the thriller aspect, adding to the suspense and emotional weight during critical scenes. Cinematography by R. Velraj captures the rural landscape vividly, contributing to the film's authentic atmosphere. Overall, the movie balances its romantic and action elements with a socially relevant message, though some moments could have benefited from tighter editing.

Siddharth: Delivering a restrained yet impactful performance, Siddharth convincingly portrays the determined and protective Shakthivel.

Ashrita Shetty: Ashrita Shetty impresses in her debut role as Manimegalai, bringing innocence and strength to the character.

Kay Kay Menon: Kay Kay Menon stands out as the antagonist, delivering a menacing and intense portrayal that adds depth to the conflict.