...which shall in the rest of this review be referred to as KVPR for sanity's sake.

So KVPR is the mega-budget epic new historical action film. Mega-budget in Malayalam film terms is probably still several orders lower than the cost of the average "Akshay Kumar as Punjabi Munda" vehicle, but has been used here to provide large swathes of spectacle. The eponymous character (played by Mammooty, one of only two Malayalam movie actors known outside that state) was an 18th century king of the Kottayam province. While he had a long standing history of warfare (including fighting alongside the British against Mysore), the film mainly concentrates on his period of resistance to the tyranny of the East India Company and the sustained campaign of guerrilla warfare he waged against the British with forces combined from several factions. That's probably because it's more viable to do a historical about a heroic Indian ruler rebelling against the foreign invader than on one provincial king against another. Also, Mammooty would fit better into this phase of the Raja's life when he was in middle-age.
The story is constructed mainly a series of encounters between the forces of KVPR and the British (and their allies). To the film's credit it has a mostly handsome look (Although the wigs for the British characters are horrible) and the scenes of battle are executed with a good deal of energy – wire-work and CGI are used in good amounts here – which makes the film an amusing visual trip (considering the technical limitations of the Indian film setup).
On the other hand, the film's enormous length (almost 200 min), repetitive sequence of events and MT Vasudevan Nair's disappointingly simplistic treatment of its characters (the people that support KVPR are the good guys, while the British and their allies are cringing caricature slimy bastards) make it not worthwhile for anything apart from the scenes of combat.
So on the whole it's a decent action-focused period piece, and if you like this, you ought to check out similar but significantly superior efforts like Thailand's Bang-Rajan...or best, the Japanese masterpiece Seven Samurai.