First of all, do not fall for negative reviews. Most of them are paid to write stuff.
The movie is not boring. The concept is really good, one of its kind in India at least. Its about a girl who is addicted to social media and ends up buying a mysterious phone which turns her life upside down. In this movie, there is not much emphasis on exorcism but on science which is one of the reasons what makes this so unique. The concept of physics and electromagnetic waves and its impact on containing the negative energy. We cannot deny that negative energy does exist, which most people term as supernatural encounters or ghosts. If you have no belief in those, then this movie may disappoint you.
From an acting standpoint, Manju Warrier does a fantastic job. She has the kind of innocence and realism which makes you empathize with her character when she realizes that her days are numbered.
Compared to Cold Case, this movie stands out in terms of concept and execution.