In a single line it is a good movie, mostly due to the visuals, background score and action sequences.
Delving deeper, the story starts off slowly with Kochunni's youth. However the buildup is focused more on establishing him as a good guy and his relationship with Janaki. It has 2 song sequences here which do not add much to the movie.
The story leaves a lot more to be desired, as it looks no more than a string of loosely connected events, especially in the first half. The second half is more fast paced and action packed.
Mohanlal's depiction of the extremely eccentric ithikkara pakki is simply superb. Sunny wayne and other actors have been under-utilized though, again partly down to the script.
The movie however is a something of a visual treat. The colors, costumes and sets gel in very well and manage to paint a very good picture of 19th century Kerala. The underlying themes of caste discrimination and british rule mix in well with the movie.
Direction too is not very flashy, however some action sequences could have been watered down.
Overall, with a better script it could have been a classic. However this a good movie and totally worth a watch. Nivin fans can boast about this performance, though premam would still top imo as his best movie.
Special mentions: Babu Antony, Shine Tom Chacko and the Kalari moves used in the movie.