Rise of the Ynnari: Ghost Warrior 5/10
Something about it just didn't inspire me - maybe the eldar were just too human. Also, plugging in one of the villains saying "make NNN great again" was really cringe-worthy. There's a difference between having political relevance and shunting the reader out of the story. But when the book worked, it worked.
The Last Hunt 8/10
The ending was a bit too tidy, but generally, it was a very solid book with a great feeling of atmosphere.
Ferrus Manus: Gorgon of Medusa 9/10
This one is still in flux. In general, it was a phenomenal book. The downside was the portrayal of Ferrus being insufficiently awesome, so to speak. Ferrus needed a portrayal that showed why he was chosen to lead seven Legions at Isstvan, and this wasn't it. At all.
Perturabo: Hammer of Olympia 1/10
The rest of the book was decent, the hrud were fittingly scary, but the portrayal of Perturabo was so abysmal as to break any numerical scale. I think Haley is just bad at writing "left-brain" characters - he writes Guilliman badly in Dark Imperium, and this abomination is even worse.