What I got aside from the generic solid codex, msu army, in-your-face:
- 4++ on haemies
-reavers are supposedly awesome, they move 18", still advance 8" and can then charge, I don't know if that requires stratagems, specific faction however, but definitely a can-do
-lightly implied that one cult trait could be advance+charge (allowing the above)
-strongly implied (everything is "strongly implied" let's not say that anymore) bonus for pure kabal/coven/cult detachment
(comparison with daemon locus), likely it's just the <faction> trait that only works on a full <faction> detachment
-Trueborn are not an entry in the codex (what ???)
-Coven with armywide -1 AP in CC (likely a faction trait)
-leaving the first turn to a drukhari cc list, not a good idea (apparently)
-Drahzar fights twice in some way (compared to berzerks)
-mandrakes and incubi not being linked to factions doesn't work too good for them (obviously linked to full faction detachment boni)
-they did say drukhari were a decent cc army
That's all folks, grab your salt and cya.
http://www.thedarkcity.net/t17149-v8-codex-tidbits