Having read many negative reviews, I went in with minimal expectations. The first half seemed to lack cohesion, but the second half more than made up for it. Yet someting was missing in the movie. I think it would have worked better if Maniratnam had stuck to the relationship between Veera, Ragini and Dev instead of layering it with tribal angst, class struggle, etc.
Most of those who read this blog might have read the story Saba Vimosanam by Pudumai Pithan written in 1940s. If not you can read it here. The story revolves around Ahalya, who was relieved of her curse of being a stone after Rama's feet touched her. After Rama returns from Lanka, Sita and Rama come to their ashram. Sita tells her story to Ahalya. Ahalya erupts when she hears that Rama doubted Sita and asked her to undergo agnipareekhsa. She turns back to stone not wanting to be at the mercy of Rama, who doubts his wife.
Kamal wrote a story around the agnipareeksha issue a few years ago. The story is about agni falling in love with Sita. I had translated that story here.