First of all let me say that Nani's acting was on point! If you see anyone saying otherwise, don't believe them.
The reason for 3 stars is simple: the story is nothing special - It was slow, predictable, and a bit boring at times...
The effects were great and Sudheer's acting was good as well, but I guess I went into it with too many expectations and barely any were met.
Long story short, if you want to watch a movie with great acting, good visuals and a serial killer, this is the one to turn to.
But you really wouldn't want to watch it more than once.