Kaadhal Kirukkan has its roots in a Hollywood film, which was also then remade into a Hindi film. The Hindi version was definitely inferior to the original, with its need to adhere to the Bollywood formula. But it had some strong performances, especially by the protagonist, that made it entertaining, and was well-made overall. But director Shakthi Chidambaram's unfamiliarity with the thriller genre, Parthiban's unsuitable performance and a silly comedy track make Kaadhal Kirukkan quite a few places below the Hindi version too.

Maha(Richa Pallod) is the most popular singer in a music company and when the company's owner is found murdered on the beach, her childhood friend Saravanan(Parthiban) is arrested. Maha is convinced that the soft-spoken, gentle Saravanan could not have committed the murder and hires Gautam(Vineeth), a popular and successful lawyer, to prove the same. Gautam, with the help of a psychologist(Devadharshini), finds out that Saravanan has a split personality and that it was his other persona, the violent and taunting Pazhani, who committed the murder.

Most of the blame for the movie's failure lies in the hands of the director. He had a good story with several good twists and lots of opportunities for providing thrills. To make his job easier, the story had also already been 'Indianised' for its Hindi remake. But he still fails to make an engaging movie. The movie lacks the well-paced handling that a successful thriller requires and important scenes that should engage our attention seem lame and never have an impact. Making things worse is the Vadivelu comedy track that is completely out of place. Shakthi Chidambaram, who has lighter movies like Ennammaa Kannu on his resume, would do well to take a few lessons from Selvaraghavan, the director of Kaadhal Konden, if he ever attempts to tackle this genre again.

If one focuses only on the main story, forgetting the detours into the comedy track, the movie manages to maintain the suspense about the killing quite well during the first half. Parthiban's soft demenour and proclamations of innocence are believable and we are kept wondering about the person and reasons behind the muder. The romance between Vineeth and Richa is low-key but enjoyable. The split personality theme is also something new to Tamil cinema and takes the story in a direction where we are not sure what would happen next.

The intermission marks the point at which the original Hollywood movie ended. But the story has been developed in an interesting manner from that point on (though the credit for this obviously goes to the storywriter of the Hindi version). Parthiban's plan and Vineeth's counterattack are clever and a few more sequences along these lines might have helped. But the climax is weak and predictable.

This is the second movie after Sabaash where Parthiban's styles of acting and dialog delivery work to the detriment of the movie. His dialogs after the transformation into Pazhani are delivered in his usual style and seem aimed at raising laughs rather than being scary. Richa Pallod seems lost while Vineeth is adequate. Vadivelu's comedy track tries to capitalize on previous encounters with Parthiban made famous in movies like Bharathi Kannamma and Unnaruge Naanirundhaal. But Parthiban's character here and the serious nature of the rest of the movie makes the track completely out-of-place and therefore, less funny than it could be.