Let me start with Cinematography, it has all the recipe of Hombale films. The producers of Kaantara!!
The treasure hunt kind of a story with some supernatural healing element is fine but the non linear presentation across three time periods doesn't stick well. Tovino Thomas does justice on part but the plot does not draw that stickiness which a Kaantara or a Baahibali does!
Music some times is sometimes superfluous or overwhelming.
The story line is all about lineage and legacy, and says how the protoganist negotiates his way forward to erase the untrue legacy. Basically the protoganist trio are ready to face all odds for greater good. While that theme is good it needs a proper presentation.
Kalari was shown well initially, even during the climax it's brought in and presented well, initially but loses steam almost instantly.
We are left to wonder what is it that the hero will use to win all the odds against him. It's finally the supernatural saving element in the plot that makes the entire much a do about something into some what nothing.
Needn't have to be that lengthy a movie to say what you wanted to say!! Though there are a couple of twists in the movie they don't appeal much.
Overall you can watch once with some supernatural support for almost 3 hours.