I think the concept is really interesting. At first I was expecting something supernatural where the boy is actually the ghost of her dead son, but the story heads in a completely different direction.
It's more of a mystery series, where the main protagonist, scarred by trauma, is absolutely clueless about everything that's going on. It really shows how much of a control our emotions can have on us. The ending may be a little bit disappointing, but I think it's actually really realistic. Meena's story could have had a better ending, but her trauma hurt her so much that her son is the only thing that keeps her going, no matter if said child is not truly hers.

The story is really articulated, although after a certain point it becomes predictable. Although I think the story is really good, I think they should have expanded it a little bit. For instance who's Tom's uncle? Why was Arm thinking of killing him? How did Arm and Tom meet? Is their striking resemblance just a coincindence or they may actually be related? Who was part of their sadistic game, besides the boy wearing glasses (can't remember his name)? When did Pete join the scam scheme and why did he hate her wife so much?
I think the fact we don't have an answer to these questions doesn't spoil the story, but it would have still added a little more flavour.

Maybe it's not the best series out there, but I think it's still enjoyable. Recommend it.