Kamalhassan deserves praise for his courage in accepting this role. Sridevi has the livelier, more visible role that also offers greater oppurtunity for histrionics because of the nature of her character. Kamal has to underplay his part and almost play second fiddle to her most of the time. It is only in the climax that he gets the oppurtunity to display his limitless talent. But in the end, he walked away with the National Award for his role(his first of three) while Sridevi was left awardless (soon after the awards were announced, Kumudam had a cartoon titled "What people are thinking" which showed Sridevi deciding that from then onwards, she was going to act only with actors like Pratap Pothan so that her performance gets noticed!).

When Lakshmi(Sridevi) is involved in a car accident, she ends up remembering only the events in her life that happened until she was six or seven years old. Fooled by some evil men in the hospital, she ends up in a brothel where Srinivasan(Kamalhassan), also called Cheenu, a headmaster of a school in Ooty, finds her. Realising the sorry state she is in, he takes her back with him to Ooty and becomes her self-appointed guardian. Theirs becomes a symbiotic relationship, she relieving his loneliness and he, saving her from the big, bad world. The police catch up with them just as Cheenu takes her to a local homeopath who gives him hope of curing her.

Sridevi astonishes us with her performance and proves that glamor need not necessarily be at the expense of talent. When playing a mentally retarded patient, there is a very thin line between acting and overacting and she remains on the right side of this line always. Her fear when Kamal nears her in the brothel, her anger when he rebukes her and her innocent giggle when he makes her laugh are all completely genuine and captivate us. Its a tour de force performance and every frame she is in reveals another facet of the character. Kamalhassan starts off easy and gradually increases his emoting before finally peaking in the climax. His facial contortions when he acts like a monkey, both in the climax and before, are amazing. The climax, starting with his run down the mountain(his fall over the car and into the mud seems to have been done by him and not a stuntman) and ending at the train station, is one of the longest, sustained acting performances I remember in tamil cinema. At the end, as he lies on the platform, you can see that life has drained out of him.

The relationship between Kamal and Sridevi is the heart of the movie and very cute. There are several laughs here as she earns his ire and turns to Seetha Paatti for support or enjoys his 'monkeying around'. A cute little dog that Sridevi names Subramani, also takes part in the fun. The sequence where Kamal searches for her all day only to find her sitting at home when he returns and his dream where a cured Sridevi dresses up in a sari and attends to him, are touching. The climax is one of the strongpoints of the movie. Kamal's attempts to catch Sridevi's attention are brilliantly performed and very touching. When he cries as she throws him a coin thinking he is a beggar and then walks into a lamppost, the impact is forceful. The entire climax is emotionally draining and its impossible to not have a lump in the throat as Kamal calls after her and walks in the rain, alone and weary.

'Silk' Smitha appears in an unconnected track as the sexually frustrated wife of an old husband and has her eyes on Kamal but he resolutely resists her bold advances. Though completely unnecessary and having no bearing on the story, one positive aspect of this line is that Balu Mahendra treats this track seriously and does not introduce cheap comedy in an attempt to bring a comedy element to the movie. So the sequences are not as irritating as the ones in the track in Idhayathai Thirudaathey . The Ponmeni... song sequence is picturised very well with Kamal and Silk dancing on the greenland. The number is quite erotic but never vulgar.

Music and photography are two more pillars on which the movie stands tall. Balu Mahendra is probably the only well-known director who had Ilaiyaraja as the music director for all his movies and Ilaiyaraja responded in kind with some brilliant songs for his movies. Here he shines in all the songs and the background music. Kanne Kalaimaane..., which incidentally, was Kannadasan's last song as lyricist, is so soothing and comforting while Poongaatru... is also melodious. Kamal and Sridevi have a lot of fun during Munbu Oru Kaalathila... while the whole track involving 'Silk' Smitha can almost be forgiven for Ponmeni Uruguthey.... Vaanengum..., which opens the movie, is probably the least known of the songs but is very catchy. Balu Mahendra, also responsible for the photography, makes Ooty come alive in all its natural splendor. His camera captures the vivid greenery lovingly and takes us right there.

In the sky of tamil cinema, Moondraam Pirai shines as one of the brightest full moons.