Carl Dremmler is a fantastic character that actually is every bit the sad, pathetic man that audiences kept forgetting Rick Deckard was because he was played by Harrison Ford. No, Deckard is a scumbag who murders people he knows to be innocent thinking beings because it would be inconvenient to resist the police shaking him down.
While I'm not going to say Jon Richter manages to match Phillip K. Dick's even more despicable version of Deckard from DO ANDROIDS DREAM OF ELECTRIC SHEEP, there's being a really good boxer and boxing with Ali, but he manages to go the extra mile in creating someone who really is lost in the noir haze of his world without hitting, "I am a protagonist of detective fiction." Which is to say Carl Dremmler is believably sad and pathetic as a bachelor who lives alone in his apartment with his sex bot and terrified of the outside world that has left the majority of humanity behind.
The Auxiliary's premise is London has been all but taken over by an integrated AI that now handles the entirety of the internet as well as everything linked to it. TIM AKA The Imagination Machine is supposedly not sentient but handles drone deliveries, electric cars, and all of your media preferences ranging from Rage Against the Machine to the latest K-Pop. I think 2039 is a bit too early but I'd state that the world is a somewhat believable one for 2069. In any case, I'm hardly one to complain since my favorite cyberpunk movie, Johnny Mnemonic, was set in the far off year of 2021.
Carl hates his job and has the somewhat cliche excuse of a dead child to explain why he's lost in a bitter self-destructive spiral of depression but this is the only misstep I think in an otherwise incredibly strong narrative. The case is also suitably intriguing where a man's cybernetic arm apparently murders his wife of its own accord. Can TIM be hacked? If so, does that present an existential threat to London's economy as well as way of life.
Is it grimdark? Yes, I'd actually say it very much is. Like Deckard's literary counterpart and his movie one to a lesser extent, Dremmler has a darkness to him and is primarily motivated by his grievances versus any real sense of justice. The world is corrupt, self-serving, and at times actually nasty. He's frustrated both sexually and well as emotionally, which leads him to lash out with violence. However, the culture that surrounds him is so harsh that you want him to succeed against the forces arrayed against him.
There's layers of corporate conspiracy, paranoia, religious fundamentalists, 3D printed bugs, assassinations, and other weirdness that works excellent for this story. The ending is also incredibly powerful and unexpected. I strongly recommend this story and think people who like dark, gritty, and dangerous sci-fi will enjoy it.