The Guardian gave it 4/5.

I really enjoyed it. I think the drama was toned down on purpose to reflect the painstaking reality of forensic investigation. It's not exciting but it's often the evidence that is key in a prosecution. It took them quite a few years to gather the DNA and other forensic evidence and put the pieces together, the whole mood reflected that for me. If you had Luke Evans getting massively animated and jumping over cars for no reason, wouldn't have been the story they were trying to tell.

Plus I liked that they used Port Talbot for the scummy scenes where the son lived