I hesitated on this one because generally depictions of mentally ill people are pretty bad. While I cannot in anyway say I'm an authority or have lived experience with this kind of mental illness, I do know that, while also solving a fairly interesting and complex case, in which River's partner was murdered-it also manages to paint a humane portrait of a mental ill person. He is ostracized but highly functional and empathetic and kind, while also having to contend with his illness.
The production values are great. The acting is solid. Locations and cinematography and wardrobe are great. Best of all though, as is rarely the case, the script is great. The plot feels fresh, as do the beats. It has a lot of breathing room, as most British drama does. Some of which always feels like it could be truncated, tbh. But it undeniably strikes a chord; far more so than American conventions manage. It's subversive of the genre and of stereotyping the mentally ill.
It's just solid all around, really. That, plus, the audacity of subject matter and unconventional protagonist and emotional portrayal, make it almost perfect, for me. Highly recommend it.