Just okay. I would give it 2.5/5.
It was interesting untill the serial killer becomes a god like figure. It's really too much after a certain point that the entire CBI team is so helpless and struggles to counter every move of the killer. At no point of time they had any advantage or upper hand over the so called Asur. Naina an ordinary software Engineer has so much knowledge about hacking that without her help CBI cannot do anything, looks childish. There are lots of flaws.
If it would have been a simple story without making the killer's actions as a potential global catastrophe and make it look super natural, it could have been an interesting watch.
Edit: Season 2 is pathetic.