Judging by the number of bicep tattoos I've seen, Khorne is the most popular of the chaos gods. 
Judging by the number of models I've seen on the table, Khorne is the least popular of the chaos gods. 
And now here I am, judging Khorne.  I'll be up front - I've played a lot of CSM and a lot of Daemons, but I ain't never fielded no Khorne.  However, I understand how an assault army works, and guess what?  The most predictable god likes to smash lots of bodies into the opponent.
Today we'll be looking at what the codex adds (and doesn't add), what seem to be the standouts, and some sample lists.


First off, the bad news: these are the same stat lines and point costs from the CSM and Daemons books.  Daemons have lost Daemonic Instability and gained fearless, which is great.  This means Heralds/Lords can join marines/daemons.  But it also means that we shouldn't be expecting a new CSM book in our lifetimes, or at least not one that addresses the overall low-tier quality of the CSM book.  It also points to no update to the daemon codex, which is good for those of us who play daemons and bad for those that don't.
Errata - CSM MoK now gives counter-attack, which is great.  There are three varieties of Bloodthirster, which is pretty cool.  One has a D strength ax, which is awesome!  Rhinos are fast attack choices.  The mutation chart is gone, but all character must accept/declare challenges.
The major new special rule that Daemonkin adds is Blood for the Blood God! and the associated blood tithe table. Yes, this is the first special rule with an exclamation point. Whenever a unit containing at least one model with BFTBG! is completely destroyed and/or a character with BFTBG! is destroyed, you gain a blood point.  So yes, an independent character dying is worth two blood tithe points,
The blood tithe table cashes these points.  It gives some buffs that get better the more you spend on it, topping out at sacrificing a CSM character to summon a bloodthirster or daemon prince.  However, since it will probably be at least turn three before you could get a free bloodthirster for eight blood tithe points, and he can't assault before turn 5 in that case (you cash these points at the start of the turn, it arrives swooping, can't change flight modes first turn, can't assault when it changes modes), you'll probably be better off using the 2, 3 & 4 point options (note: these only affect units with BFTBG! so any allied units from CSM/Daemons cannot benefit).  Two points gives your Daemon units Rage to supplement their furious charge, and your CSM units furious charge to supplement their rage.  Three points gives everybody FNP.  Four points adds one to everybody's attacks.  Pretty awesome, and, if timed right, can totally swing a game.  5 & 6 give you bloodletters, flesh hounds, skull cannons, bloodcrushers.  Again, not going to come in early enough to swing the game, especially when you can get their worth in attacks or units survived from lesser investments.

A big change to army composition lately is the "Decurion," so named of course because Necrons did it first.  Here, it's the "Blood Host Detachment."  These are basically flow charts or choose-your-own adventure army composition.  You have some mandatories at the top, then some optionals at the bottom.  In the BHD, they are led by a Bloodthirster (flavor of your choice(optional)).  Then you MUST take a slaughter cult,  Then you can choose 1-8 of the formations and/or "War Engines."  The big benefit from taking this is you generate an additional blood tithe point every turn, before you spend them.  It also makes the army battle-forged, which gives all your formation troop tax ObSec.
The formations are:
Slaughter Cult -  HQ(not special bloodthirster), 2-8 marines/letters/zerkers, 1-4 possessed, 0-2 cultists, 0-2 spawn. The possessed tax sucks, but you can destroy your cultists if they fail morale (to get blood tithe points, deny maelstrom missions), and
Brazen Onslaught - 1-4 terminators, 2-4 bloodcrushers.  At least they put two of the worst units for in the same formation.  Basically they get rampage.  Just no.
Khorne's Bloodstorm - 2-4 raptors, 1-4 warp talons, 0-1 heldrake.  Add +1 to HoW or Vector Strikes.  Again, overcosted, poor performing units except the Heldrake.
Gorepack - 2-4 Bikers, 1-4 flesh hounds.  Hounds get HoW, bikers get shred on HoW, everybody gets Preferred Enemy(psykers) and Move Through Cover.  Hell to the double yes.  I love some flesh hounds, and chaos bikers have needed MtC for a long time.  This will definitely see some competitive play as a MSU formation.  I would probably add it to my current daemons list by removing a few screamers to get two packs of minimum strength bikes and to add fearless hounds.  I've lost too many to instability!  Since the hounds typically do some serious murder, I could conceivably pull an additional summon off of blood tithe points.
Charnel Cohort - 1 HQ(not DP/BT), 2-8 letters, 1-4 hounds, 1-4 bloodcrushers, 0-4 skull cannons.  The HQ re-rolls reserves and units from the formation don't scatter within 6" of it.  -2 to fear checks in the 1/10 games a unit takes a fear check.  Counter-Attack.  CA is awesome, but the bloodcrusher tax sucks, and it's easy to have a bubble wrap of cultists or hounds if you are going to soak a charge. In fact, just pay for the wrap instead of the crushers. 
War Engines - Maulerfiend, Forgefiend, Soul Grinder, Defiler.  I don't have any maulerfiends, but every single battle report says they die the first turn.  I'm sure if you had four of them, one or two might survive to die the second turn.  For my money, it's all about soul grinders with baleful torrent.  Seriously, there are few armies that could stand against eight of these monsters.  More seriously, there are fewer people who have eight soul grinders.
Wargear -
Some real stinkers, and some real standouts, as we have come to expect.
Icons of Wrath - add 1 to assault results.  Gives your CSM furious charge and a re-roll on charge range.  A must buy for 'zerkers and CSM.  Basically a 20 point tax.  Tax is annoying.
Banner of Blood - add 1 to assault results.  Gives your 'letters a 6+d6" charge.  Basically a 20 point tax.  See above.
Goredrinker - S +1 AP 2 unwieldy.  Gets more powerful the more the bearer wounds, topping out at S10 instant death at eight wounds.  Could be paired with a power weapon to make sure he don't die to massed assholes.
Blood Forged Armor - 3+ armor, FNP, Eternal Warrior.  Pretty cool for a lord, might work on a herald but they only have two wounds.  Probably put him on a juggernaut, but then he gets a bit pricey.  A lord on a bike or juggernaut with this would be truly worthy of his attentions!
Blade of Endless Bloodshed - power weapon that adds a blood tithe point if the bearer inflicted any
casualties.
Kor'Lath - S user AP2 not unwieldy!  Instant death on a six, and you get a free bloodthirster if the bearer dies!  Well, it loses d3 wounds a turn (++ allowed) but still super awesome!

Pretty solid codex overall.  I hope this points to more cult marine releases.  Khorne was definitely not viable before this, and I can see them winning some games, even some really competitive games now.  Fearless daemons is big, because you can still lose combats, especially multi-assaults, and then get punished by the dice gods.  This book takes that out, as well as the annoying warp storm table and random rewards.  There's plentiful FnP for these blood-crazed madmen across the board, though I feel the CSM side is still quite weak and basically a tax for the superior daemons.  The book has no place in it's special detachments for IA13 vehicles, which is a shame, and a CAD would really be wasting the strength of the book which is the Blood Host Detachment.  The blood tithe table is clever and fluffy while still looking to be effective, a real accomplishment for GW.

Some list ideas -

Just a Gorepack 1845 -
Chaos Bikes x3, PF, 2x Melta
Chaos Bikes x3, PF, 2x Melta
Chaos Bikes x3, PF, 2x Melta
Chaos Bikes x3, PF, 2x Melta
20 Flesh Hounds
20 Flesh Hounds
20 Flesh Hounds
20 Flesh Hounds
Total board denial with those 50mm flesh hounds (as based in the book).  The bikes will probably die before they deal with what they're there for, but any army will have a hell of a time chewing through these 172 wounds.  Will (maybe) lose to knights, will have a good chance against anything else.  Remember, flesh hounds scout and are fleet.

Grind! ~1850, battlescribe is sometimes difficult
Blood Host Detachment
  Slaughtercult -
    Herald of Khorne, Goredrinker, Locus of Fury, Juggernaut
    20x Bloodletters, Banner of Blood
    8x Bloodletters
    5x Possessed, Rhino
  War Engines -
    Soul Grinder, Baleful Torrent
    Soul Grinder, Baleful Torrent
    Soul Grinder, Baleful Torrent
    Soul Grinder, Baleful Torrent
    Soul Grinder, Baleful Torrent
Allied CSM
    Chaos Lord, Power Weapon
    10x Cultists
    Spartan Assault Vehicle, Ceramite Plating, Legacy of Ruin that gives Khorne Daemons +1 invulnerable within 6"

This would actually be brutal.  A wall of five grinders with a 4++ giving the Spartan a hull down as they flame and dakka their enemies. Then 60 S5 AP3 attacks plus the herald's hate when it disgorges.  This would give any enemy a real headache.  The possessed, small squad of letters, and cultists hang out in back and earn the blood god's eternal scorn.   Or maybe they brought something to kill. Also will completely fill your deployment zone.

That's all I got, I might try a go at this grinding list and see how it shakes out.  Anybody out there used this yet?  Jazzed about the new doctorate in Khornology?