This Codex includes all the lore and rules for the Drukhari in the tenth edition of Warhammer 40,000.
The lore section of the book covers the history of the Drukhari from before the Fall to the Era Indomitus reasonably well, as well as giving information of Drukhari tactics, technology, society, and the units available to use in the game itself. All this lore is quite interesting, and includes quite a bit of nice information on Commorragh, the Dark City. The part on the weapons Drukhari is also very good, with some great illustrations.
The artwork in the book is generally very good, although the double page spread showing the Drukhari fighting the White Scars has some very odd perspectives that make the Space Marine Impulsor transport look wider than it is long. The model photography in the book is also as good as usual, with a reasonable nice mix of images showing warriors form the Kabal of the Black Heart and the Kabal of the Poisoned Tongue. Seeing full Wych Cult and Haemonculus Coven forces in colours other than the Cult of Strife and the Prophets of Flesh would have been nice though.
The rules in the book seem relatively good, with the Drukhari’s Power From Pain Army Rule being particularly interesting as it allows you to earn tokens during a game that can then be spent to Empower units, with each unit having their own Empowered ability. While this is a little less simple than some Army Rules from this edition, it is nicely in line with the lore. The Detachments available for Drukhari players are pretty much what I thought they would be (the combined arms Realspace Raider, the mechanised Skysplinter Assault, and the Wych, Haemonculus and Kabal focused Spectacle of Spite, Covenite Coterie, and Kabalite Cartel respectively) and all of them seem as good as expected, as do the Datasheets for the units themselves.
The Combat Patrol force included in the book seems relatively good, but it is focused on my least favourite Drukhari sub-faction, the Haemonculus Covens, so I am not too interested in it (plus it consists of every Haemonculus Coven model in the current range so there is little to say about its composition).
The narrative Crusade rule for the Drukhari are pretty much the same Ascendant Lords rules as in the previous edition where a player gains control of territories in the Dark City to gain bonuses, but with the Spoils of Battle rules being replaced by Rival Lords who the player competes against, which seems quite cool. The rest of the Crusade rules are mostly new for this edition, with those that have appeared before being redone.