So the dust is still up in the air, but I'm going to venture forth with some initial thoughts and reactions.
The death of alpha strike?
One consistent theme is the nerfing/elimination of many of the mobile burst damage combos in the game - KO Khemist stacking, Tretch + Skaven Warlords stacking, Sayl + X alpha strike, Stonelord alpha strike and even Cloak of Mists and Shadows on the Ghoul King on Terrorgheist. There are only a handful of really strong alpha strikes/burst damage melee combos left that spring to mind: Murderhost, Shock Gauntlet Storm Fiends with Packmasters, very expensive Tomb Kings and Warherd, Executioners with the Hurricanum, Skyborne Slayers and Hammerstrike Force.
The question this raises is whether the move towards hordes and away from alpha strike means that the meta shifts back towards bunkers (and specifically Order Funlines). I'm concerned about Freeguild getting even more stand and shoot with their units giving out +1 to hit buffs like candy (already a powerful mechanic). The nerf to the Hurricanum is very necessary now.
Battalion changes and Hordes
Some good news for Death - almost all Battalions got jacked up in cost. This really changes the calculations for listbuilding - now you really have to pay a lot for that second artefact, rather than getting 3 easily. Single drop armies will be much rarer and there is a real trade off between models and battalions. In some cases, the cost increases are offset by cheaper battleline and/or volume discounts on hordes - best example being Sylvaneth.
The Big Losers
- Mixed Destruction - headshots to the Kunning Rukk and a multi-pronged attack on the Stonelord (points vs other big monsters, halving wounds nerfed, Talisman nerfed and possibly the Battlebrew not affecting the mount - this depends on how explicit the reference to the mount should be).
- Mixed Death - the removal of the 5++ is devastating to Death's survivability. Death still don't have any credible way to reach out at range - indeed they have lost the Cloak teleport too (and Little Mannfred on a Balewind). The only good news for mixed Death is their non-reliance on Battalions, while everyone else is paying significantly more for these.
- Inherent Battleline - as they don't count as Battleline if they are allies. Effectively only used for Order, Death, Destruction, Chaos allegiance armies.
- Brayherd - the only positive is cheap as chips Bestigor spam, but the command ability of the general (absent named characters) is dire. They might be able to spam bodies in your face, but not as well as other armies.
- Kharadron Overlords - death by a thousand cuts for one of the most overpowered armies - the Thunderers are now rifle spam units, who are still decent output for the amount of ship capacity they occupy. Drill cannons have been nerfed by a third. Khemists don't stack and are 40 points more expensive. The Navigator lost his 3D6 unbind (which was a bizarre change). No cost reductions at all is painful (Gunhauler and Frigate).
- Bow Hunters - just not worth the points. They can at least move out of combat using Navigate Realmroots and still shoot (not a retreat).
- Crypt Horrors - seem like a bad choice compared to their flying mortal wounding, rending Crypt Flayer cousins.
- Mannderp - cannot be an ally - still Derpy Mcderp.
- Skyfires - I still feel 220 would be right - 3 Flies are 220.
The Big Winners
- Daughters of Khaine A big point reduction on 30 Witch Aelves together with the lack of a ban on stacking buffs means 90 bodies with a quadruple 5++ Ward Save is now a thing - that's 80% of damage protected. Even just for the first Battleround this is meta-breaking. They can also spam Battleshock immunity and other buffs.
- Fyreslayers - the change from the truly dire Order Allegiance pack is immense. The Rune mechanic is exceptional - especially the across the board rend - I also like the extra throwing axe range, since this will buff the damage of 30 Vulkites and 30 Aurics popping up to say hi. Some of the cost reductions have been rolled back, but they are still cheap. The Vostarg Lodge is a win as it means that all your units will definitely be able to fight in melee for a battleround. The other battalion feels like a miss as it neglects the fact that the army can deepstrike with Runesmiters. Battleshock Immunity Bubble is nice. Artefacts aren't great.
- Freeguild - what was already a decent army has moved from the terrible Order allegiance to an exceptional new Allegiance pack. The battle trait expands stand and shoot options, which is already an infuriating mechanic (small models that can fly can partially mitigate this). They have a carbon copy of the Stormcast's incredibly strong Staunch Defender trait (called Indomitable - only it stacks with cover!) as well as solid artefacts - Armour of Meteoric Iron is a straight +1 save and Writ of Dominion is a once per game aoe wound buff). They also gained a cost reduction to their Griffon, which was already amazing value for 300.
- Legion of Azgorth - lots of subtle buffs. Cost reduction for the Bull Centaur Renders is strong - 60 wounds worth for 640 points with -2 rend, 2 damage. Take a Sorceror Lord as an ally and buff with reroll 1s to hit, wound and save.
- Slaanesh - so exciting - the triple general trait looks very tasty (e.g. take Archaon as one, but you still get a battle trait) or take two traits on your new shiny Exalted Greater Daemon of Slaanesh. The traits look strong too - especially the copy the Yhettee ability - you can stand out of combat at 4" away until the end of the combat phase (rather than charging), then pile in 6" and smash face. Supremely Vain is also a nice buff. Icon of Infinite Excess is a situational but amazing once per game aoe buff +1 attacks to all models including enemies - or summoned Bloodletters! Breathtaker looks good as a quasi-Forest Dragon toy.
- Ironjawz - I would defer to @Chris Tomlin 's superior knowledge here and excellent write up here - They have a copy of the (nerfed) Destruction move (a good change as it's much quicker than rolling for a Warmachine, rolling for its crew....), two sweet Battalions, the ability to chain activations if they wipe out enemy units (which creates a good tension between MSU and big units for both you and your opponent). Lastly there are material cost reductions for the Cabbages and Pigs (how are they less than 10 points per model!).
- Seraphon - look very nasty - can teleport Kroak into the front of your army and then Balewind and aoe spam against them. Same trick with Razordons (which got cheaper). Solid traits and artefacts.
- Stormcast - the nerf to all the overpowered mixed Chaos, Death and Destruction traits is a big plus for them. The availability of 2+ rerollable saves is a big advantage given the nerfs to burst damage discussed above. The Lord Celestant on Star Drake got a points reduction despite being a popular choice. They benefit the most from allies given their freedom to choose. Prayers appear to work on Allies (unlike Khorne Prayers....) which seems purposively wrong and isn't likely to survive long.
- Sylvaneth - As discussed, the nerfs to alpha strikes/burst damage melee combos mean that Sylvaneth's traditional grind, chip away and heal modus operandi should be viable (notwithstanding the nerfs to Hunters). Extra Battleline choices make Dreadwood viable.
- Wanderers - nice board edge mobility with their pew pew. Have a trait called Myst Walker which basically imports the 40K cannot shoot a character rule for your general. The Forget-me-knot allows you to incapacitate a charging Stonelord in the combat phase, which is hilarious. The Viridescent Shawl is decent for -1 to hit vs pew pew and a buff to nearby wizards.
- Tamurkhan's Horde - have a battalion which isn't pricey. Some units cheaper.
- Everchosen - source of cheap Battalions and Varanguard cost reduction. However, Archaon not any cheaper.
- Elite infantry in general - Stormvermin (and the costed the same White Lions!), Phoenix Guard, Bestigor, even Chosen.
- Jabberslythes - how can they be so cheap!
- The Rogue Idol - so good you can buy two in a box now. Obvious ally choice. Synergies better with Ironjawz now (Orruks).
- Troll Hag - cheaper and very solid - good spell!
- Freeguild General on Griffon - so cheap!
- The humble Treelord - cheaper.
- Drycha - got a buff to her aoe ability, so it no longer affects friendly units or here. Also good option vs hordes. Seems like you can pick which weapon she has before the game (e.g. it's not something you select on Scrollbuilder) - logically being a named character she does have the ability to do either and pick for each battle.
- Spite Revenants - might finally see the table now they are cheaper and battleline.
- Settra - now generic so trolling with the new Ring of Immortality - still a horrific amount of points.
- Neferata - now an ally choice. Cheaper.
- Arkhan - an immensely good wizard and troll.
- The Exalted Greater Daemons - with the nerf to pew pew and some subtle buffs to their scrolls, these are a real thing now.
- Mannderp - no longer costing you the 5++ Ward Save if you take as general. His Command Ability is great.
I'm ambivalent about Pestilens and Skryre. I think they will find hard counters in the form of rerollable saves; and hordes respectively. The cost increase to Tunnelling Skryre is very welcome.
I'm not convinced by Nighthaunt or FEC. The deepstrike ability for Nighthaunt in too risky and not so helpful for non-pew pew units. To be fair the Lightshard is an amazing buff on Spirit Hosts - as they only hit on 5+
Defenders of the Realm Delusion is decent to mitigate pew pew. I think Dark Wizardry is the only decent command trait - as their all important buffs are spells. The artefacts are pretty meh too - probably the gamble on the Chalice for healing D6 wounds. You can bring in a Necbromancer as an ally for Vanhels.
As for Soulblight - the fly is nice. Their spells aren't good enough to warrant taking the buff to that (Blood Boil - sigh...). The Saccharine Goblet is a quasi battle brew - probably doesn't buff the mount sadly. The traits aren't great - retreat and charge might be the winner. Mannderp and Neferata aren't soulblight, which sucks.