I posted this over at Dark Reign, ( http://vidzup.com/forum/index.php?topic=1105.0 ) but thought i'd copy it over here as well.
Disciples of the Dark Gods
OK, I’m still digesting this (xmas got in the way), but have enough to make a review of my initial impressions. £35 paid…it’ll have to be good to be worth it! 
I’ll take it stage by stage.
Appearance
Beautiful as ever. The Dark Heresy books can’t be faulted on visuals and DotDG doesn’t disappoint on this score. The layout and watermarking is just enough to evoke the right ‘feel’ without obscuring any text, and the framing and imagery is already satisfyingly familiar.
The artwork is again a slight disappointment, but only in that it is largely recycled, instead of being predominantly new images. That said, DotDG really plumbs the depths of the GW image archives with some lovely old art mixed in with the newer stuff.
Personally I’d like to see a lot more ‘civilian’ imagery, rather than the relentless gun/sword-fest, but that’s a minor quibble.
Anyway, on to content…
Chapter 1 – Shadows of the Tyrant Star
OK. Cards on the table. The Tyrant Star leaves me cold.
It’s a narrative dead end, tediously impersonal in the extreme, and frankly to me, an obvious and pointless direct ‘port of Morrslieb from WHFRP. Komus will never find its way into any game I’ll run, which is why I dismiss it as a ‘Jokaero spawning ship’… 
That said, the Tyrant Star section takes an interesting approach. Rather than actually defining things or giving the GM hard facts it presents a series of ‘reports’ – little more than fluff really – offering titbits and opinions of in-game characters that have been exposed to Komus. There’s some very nice stuff here and they are enjoyable reads, but there’s actually very little fleshed out to help the GM interested in incorporating the Komus Star. We’re left on our own here again, with a series of ‘plot seeds’, albeit presented well.
Chapter 2 - Hereticus
This chapter obviously concerns itself with the threats addressed by the Ordo Hereticus, and the chapter attempts to make it clear what that Ordo is supposed to be doing. It includes an interesting clarification of the definition of a mutant (as opposed to an abhuman) and some generics on the nature and type of cults likely to be faced.
From this opening, the chapter then leaps into a list of additional psyker talents and powers ‘more rare than those found in the Dark Heresy rulebook’. I can’t vouch for their consistency or how they actually work, but the Space Slip power looks very interesting, as does Molten Man. This section also includes a sidebar on ‘untouchables’, but these rules seem dreadfully underdeveloped and don’t seem to adequately reflect the effects of psychic blanks described in much of the literature.
The rest of the chapter then goes on to detail a number of specific cults, organisations and threats that a GM might like to use in their game. These are:
The Temple Tendency (an Ecclesiarchy cult)
The Logicians (Heretek cult)
The Pale Throng (a ‘mutants and psykers first’ cult)
The Night Cult (Necromancers)
Each cult is very well detailed with its relevant tenets, goals and beliefs; its structure and activities; an ‘Inquisitorial threat briefing’; associated stats, characters, monsters, etc.; advice on how to use the various cults, and their relation to and activities within Calixis.
This is all very useful, excellent stuff and will keep many GMs busy and inspired for months. It really is very good. 
Personally however, for me, it feels like a castle built on sand. For example, the Pale Throng is a cult dedicated to promoting and protecting mutants, psykers, etc. (it’s a bit more than that but I don’t want to spoil things too much!) It reminds me of the mutants cause on Strontium Dog (and of course the Tenebrae in Durham Red), but my reservations come from the gaping ‘roleplaying’ holes at the heart of 40k and Dark Heresy…
OK, here’s my reservation.
…the Pale Throng has since created and inspired revolts on dozens of worlds across the Calixis sector…’ (p52).
How? Since it is an organisation of heretics and mutants how have they transmitted their ideas across the sector? Do mutants have access to interstellar travel, communications, etc?
I know that’s a thread on its own, but its those sorts of undefined issues, missing at the core of the game, that undermine the undoubted value of DotDG for me. 
Chapter 3 - Xenos
This chapter obviously concerns itself with the threats addressed by the Ordo Xenos, and the chapter attempts to make it clear what that Ordo is supposed to be doing. It includes an interesting passage about the need to gain exposure to, study and understand aliens in order to assess their threat and should it be required, better destroy them. VERY interesting I think. It also defines the ‘five dangers’ posed by contact with aliens…again very interesting food for thought.
Appetite whetted, the chapter then yanks away the main course and plunges into Dark Heresy’s ‘narrow focus’; concentrating on the aliens of the Calixis sector.
It provides the most perfunctory and cursory detail about the ‘Cold Trade’ in Calixis; that being trade in alien artefacts. But the three pages worth of detail, prices, and equipment is, well, derisory really. There is also some detail later about the vastly powerful ‘Halo Devices’, but again very little detail concerning their origins, etc.
The chapter then details the Amaranthine Syndicate, the Beast House, the Cryptos, and the Curse of Solomon. These are all well detailed akin to the Hereticus cults, and provide a very useful selection of organisations for the GM to plague their players with. The Amaranthine Syndicate in particular seems to be shaping up to be a solid part of the Calixis sector and indeed the distinctiveness of Dark Heresy.
Hugely disappointing in that none of the iconic 40k aliens are even approached, let along detailed, what is presented here is well thought out an packed with thought-food for the struggling GM.
Chapter 4 - Malleus
This chapter obviously moves on to the threats addressed by the Ordo Malleus, and attempts to make it clear what that Ordo is supposed to be doing. It also proposes to takes a look at how the warp might taint humanity, concentrating on this aspect more than the actual denizens of the Empyrean. Although I couldn’t discern exactly where this was detailed.
Rituals, the talents and powers of the Sorcerer, unhallowed relics, wards and daemon weapons are all covered; but again in only the most brief manner. 
The chapter then continues, as the previous two, with a detailed list of cults for the GM to use, in this case;
the Pilgrims of Hayte (nihilists and apocalyptics)
Ateanism (an interesting ‘school of thought’ more than a cult)
The Brotherhood of the Horned Darkness (traditional ‘cowled cult’ of wealthy and privaledged…real Cthulhu stuff)
The Vile Savants (Nurgle…say no more)
The Menagerie (Tzeentch)
The Murder Room (Murder Cult…think ‘Saw’ or ‘Se7en’, or Texas Chainsaw Massacre)
Again the detail here positively drips with inspiration for the GM.
Chapter 5 – The Enemy Within
Ah. OK. So far so good, but here things start to unravel for me and its hard to remain objective.
This chapter presents some very cursory detail about the Imperial authorities in Calixis and the possible factional infighting that might occur, but still fails to provide any meaningful detail. ‘The Law in Dispute: The Adeptus Arbites’ for example once again states that the Arbites enforce the emperor’s Law, but gives us no clue as to what that might actually be…
While a less critical GM will undoubtedly find this section as inspiring as the others, for me, it represents a continuation of the ‘gaping hole’ mentioned above.
Next the chapter runs through the various Ordos, Conclaves, Cabals, and Factions of the Inquisition itself. Yet again, still we get little detail of how the Inquisition works. Aside from reference to how these relate to the Calixis sector, you’re frankly better off reading the Inquisitor rulebook and the Thorian Sourcebook, which details what DotDG only summarises.
Frankly this section feels like a draft, or a pitching brief and is severely underdeveloped. 
It would have been better left out of DotDG to make room for a bit more information on alien artefacts and how the trading of such actually works in Calixis.
Chapter 6 – The Hunted: Wanted Heretics of the Calixis Sector
A very nice little section outlining 7 major villains in Calixis. That said there are no stats included which is both good and bad depending on your perspective. But these are well realised individuals with some very interesting plot-hookery. Ferran Ghast particularly caught my eye, as he could well represent the fate of most PCs! The Burning Princess is an A+ psyker, so modelling her using DH rules is going to be VERY tricky…
Chapter 7 – The House of dust and Ash
The final chapter is an adventure intended for ranks 4-6. I’ll say little about it so as not to step into spoiler territory, except to say that the way the PCs are hooked in at the start really galled me… 
Overall
DotDG is very good, however this book is firmly aimed at the GM and should NOT be purchased by active players…there’s nothing here for you except and annoyed GM…
It feels solid and provides a surfeit of information about a variety of threats. Even the most prolific GM will find quality inspiration here, and I highly recommend it. 
However…it does feel (as I said above) like a castle built on sand, since many of the foundations its sits on have yet to be defined.
DotDG tells you that a cult of mutant supremacists exists across Calixis…but doesn’t tell you how.
It tells you that alien artefacts are traded, but doesn't tell you who finds them, who wants them, or how the former acquires and transfers it to the latter…
As a final note, I paid £35 for this book; was it worth it?
As a book and a supplement it’s a good read and highly inspiring, but it tiptoes over the holes in the core book, that I’d argue it needed to fill to make it a great supplement.
