There has been so much media reporting on this story that I have little to add, except a few links and personal comments.
STAT news has just published a great piece on He Jiankui's research timeline leading up to the story, mainly from the perspective of a few other researchers who had interactions with He during the period when he was planning, and carrying out, his human embryo work.
At this time I remain opposed to gene-editing of human embryos with the intention of implanting the embryos to result in pregnancy. This keeps in agreement with the ASHG statement on Human Germline Genome Editing.
He Jiankui's experiment was reckless for several reasons. Here are three.
First, there has absolutely not yet been enough research to prove that gene-editing methods can be safely and effectively used in human embryos without unwanted side effects that could cause harm to the baby.
Second, the particular gene (CCR5) and disease (HIV/AIDS) that were the targets of these experiments are very problematic. Inactivating CCR5 may not always prevent HIV infection. On the other hand, people who lack CCR5 have more severe symptoms if they are infected by West Nile Virus. The embryos themselves were not infected with HIV, so the editing was intended to prevent a disease that the embryos did not carry, and is preventable in other, established ways. This does not mean that HIV is not a serious problem, or that AIDS is not devastating. It just means that the approach used here is very open to criticism from a scientific standpoint.
Third, it looks like the babies' parents did not have an ethically sound informed consent process. The informed consent forms that the parents signed seem more designed to protect the legal exposure of the researchers than to inform the parents of the real risks and benefits of the experiment.