My opinion is probably in the minority here. I was a tad disappointed with the storyline and writing. I was expecting a Rajni charisma + Karthik Subbaraj's writing combination, instead the movie felt Rajni all the way. It's not a bad thing, just that I expected more.
The story seemed very thinly tied together. Characters that start the movie, disappear by the end. A flashback is used to change gears in the movie, which is just lazy writing. The story does not build linearly, instead it stutters.
I am a big fan of Kaala. It was a combination of amazing writing and Rajni. I like Kaala the best in recent Rajni movies.
Petta is a good movie, entertaining as ever, camera and picturization was top class, Rajni in top form, but lacks Karthik Subbaraj's touch.