There is not even an iota of originality in the script which has been etched from various "twin brother twin trouble" themes popular in crass commercial cinema of the 60's and 70's.
Annan Thambi is nothing but a reworked modern version of MGR's old commercial classic Enga Veetu Pillai and so many other films in the similar vein.
As the title implies 'Annan Thambi' is the story of twin brothers, Appu (Mammootty) and Achu (Mammootty). Appu is a non stop chatter box and a con man who is always in trouble. While Achu, the nice guy is a mute, but daggers drawn at his brother due to misunderstandings created by the villain masquerading as a friend Govindan (Siddique).
Their father Ravunni (Janardanan), a ballet artist separates them due to sibling rivalry and Appu is sent to live with relatives in Pollachi.
He grows up to be a lovable thug who falls for Chembakam (Lakshmi Rai), while Achu marries Lakshmi (Gopika). But soon major misunderstanding created by enemies crop up and the brothers are baying for each others blood. Just before climax, they understand others were behind their enemity, so they patch up and take on the baddies!
A very predictable and banal story from story writer Benny .P Nairambalam, and the director has tried to infuse all commercial elements like songs, item number, fights galore, sentiments and lots of slapstick comedy. It is a typical mass movie.
The highlight of the film is the comedy trio of Salim Kumar, Suraj Venjaranmoodu and Harisri Asokhan, which raises a few laughs. Mammootty does his over-the-top twins role quite efficiently.
However if you are the type who likes mindless movies that will make you laugh, cry and be entertained, then Annan Thambi is a pleasant diversion.
Verdict: Time pass