Moondraam Pirai's most poignant moment happens in the climax as Kamal watches Sridevi go away, her memories of the time with him now erased. It is an open-ended conclusion that leaves to our imagination, the lives of Kamal and Sridevi after that. Deepavali shows us why that was such a good idea. It messily creates a situation similar to that climax and then proceeds to resolve it in an even messier fashion.
Susi(Bhavana) arrives in Chennai to stay at a family friend's house. Stifled by an overly strict father(Lal) back home in Bangalore, she enjoys her days of freedom here. Billu('Jayam' Ravi) is the golden boy of the area since his father(Vijayakumar) helped the people a lot and Billu has carried on his good work. Billu and Susi fall for each other before Billu learns of Susi's sad state - she can't remember the last 3 years of her life because of an accident. She could regain her memory but that might mean that she would forget her life since the accident. And that includes her time with Billu.
Bhavana's character is casual, open and frank and this makes the romance between Ravi and her a little interesting. But their affair is otherwise very generic with Ravi fighting with rowdies, spending time with orphans in an ashram and doing those all those other things that make a Tamil cinema heroine fall for the hero. It is another of those lightweight, superficial romances that happens in the movies. It is quite entertaining as it develops but never seems serious or deep enough to make their subsequent problems affect us. Feeling for characters in a film requires that we invest emotionally in them initially but the romance between Ravi and Bhavana does not earn this emotional investment.
The film treats a person's memory like a plaything as it comes and goes according to the dictates of the screenplay. There is some medical mumbo-jumbo thrown around but it doesn't come close to covering up the silliness of the events. There is no rationale behind when and for how long Bhavana loses - or regains - her memory (how did they even know she lost her memory for exactly 3 years?!).
The film creates an interesting knot(though it owes even this knot to Moondraam Pirai) but makes a mess of unravelling it. Ravi going after Bhavana and telling her about her times with him gets on our nerves after a while and the cycle of him trying to convince her and Lal getting him bashed up carries on for quite a while (I lost count of the number of times Ravi was kicked, hit and stabbed, only to dust himself off - pull those tubes off his body in the hospital - and go after Bhavana again). But the climax thankfully avoids the route that would have made things even sillier.
Jayam Ravi makes a convinving action hero, especially since he doesn't have to shout too much. The flat, curly hairstyle doesn't suit Bhavana too well but she is convincing in her role. Devadharshini plays a role different from her usual roles, loud and spouting Madras Tamil. Lal is adequate and same goes for Vijayakumar. Raghuvaran appears in a couple of scenes as a doctor and looks quite old and haggard. Kaadhal Vaithu... is a soft, melodious number by Yuvan Shankar Raja while Pogaadhe... takes over the crown from Kanave Kalaigiradhe... from Azhagaai Irukkiraai Bayamaai Irukkiradhu for his worst singing performance.