My initial feelings on the update are actually pretty good - aside from changes to the individual warscrolls I feel like the Legion is going to be able to compete in the new edition.
First off, the Blackshard Armour allegiance ability is easy to overlook but I think its a bit of a hidden gem. Ignoring the first wound done to each unit in each combat and shooting phase is better than it sounds when you consider that this also includes the opponents combat phase. If we do a quick bit of math-hammer here, let's assume that your enemy is targeting 4 units in the shooting phase and each of the combat phases and you are negating 12 wounds a turn. Over a 5 turn game that's a total of 60 ignored wounds. Considering most lists at 2000 points have between 100-150 wounds I don't think that's a trivial amount! Plus, combining this with things like the new Look Out Sir rule just adds to the resiliency of heros...
The Burning Skies ability is a lot more situational though and not a big game-changer. That being said, against certain armies its going to have an effect. The new Nighthaunt or the Idoneth Deepkin for example where all or a large portion of the army is flying are going to be taking a number of mortal wounds out of it. Heck in the best case scenario your opponent gets psyched out and moves his units (or especially weaker support heroes) less far to prevent those mortal wounds from triggering. Look at it this way, you essentially get a chance at a free arcane bolt against each flying unit. I'll take it.
The Fireball spell all wizards get is also pretty good. It's an easy cast with a possibility to D6 mortal wounds on hordes...
For command traits, sure none are as good as the old cunning deceiver (which is now going to change I believe?) but they aren't bad either. I don't care much for the Contemptuous trait but I like Relentless for the possibility to trigger a second attack sequence for your general which could be devastating on Drazhoath, Shar'tor or the Taur'ruk. However, I think the Grotesque trait is the best here. Combine it with the new Look Out Sir and you are at -1 to hit against your general in both the shooting and combat phases - oh and throw on a new and improved Ashstorm spell on whatever your boss is fighting and you are looking at a cool -2 to hit for both shooting and combat attacks against the general.
The artifacts are ok for the most part. The Black Hammer of Hashut is meh in my opinion since there's a lot of ways to re-roll1's in this army. The armour of Bahzerak is cool as it gives the hero a 5+ ward save and I'm a fan of the Chalice of Blood and Darkness since it can spoil one of your opponents magic phases...
My read of the overall changes to the faction is that our heros pretty much all got better without increasing in points. Drazoath has a nice command ability with the 24'' battleshock immune bubble (although you'll have to be careful with his mobility), Shar'tor has a much better ability to cause mortal wounds and a situational but useful command ability when there are a lot of centaurs around. The Castellan hasn't changed and the Taur'ruk remains a beast in close combat with a 2+ (often re-rolling 1's), 3+ once he uses his command ability (although his previous command ability was likely better). The real winners in the hero department though are definitely the Daemonsmith who can throw the Blood of Hashut each turn, has a much improve Ashstorm spell, access to Fireball and can cast endless spells for a cool 100 pts as well as the Battle Standard Bearer who now gives off a permanent bubble of +1 bravery and re-roll 1's to wound at 18'' for 100 pts.
On the monstrous cav side I think the bull-centaur renders took a pretty big hit a losing their -2 rend but at least their shields always trigger on a 6 and they didn't increase in cost. I think they were probably a bit undercosted before to be honest. Although the Fireborn's are no longer summonable, they've got an extra attack, can run and charge and are unaffected by rend now for a drop of 20 points too! I think they are now viable in a lot of lists.
I feel like our infantry got a nice buff and I'm probably going to be running bigger blocs of Fireglaives and more Ironsworn now. The Fireglaives doing mortal wounds every time they roll a 6 to hit will really add up if you start taking big blocs of them and the Ironsworn's Spiteshield ability is now a lot more useful than it was now that its no longer affected by rend. Oh and ironsworn are now 10 points cheaper to boot. All in all, supported by a BSB and maybe a Castellan/Blckshard Warhost battalion I feel that our infantry can really do some work.
Artillery-wise we remain in a good position and I can't find too much to say about it. The Dreadquake isn't going to see much more use, the Magma Cannon remains an amazing choice at 140 points and I continue to like the rocket launcher for 120 points with a possible 4 attacks, 3+, 3+ when shooting at infantry blocks.
The battalions are a bit of a disappointment for me though. I'm lukewarm on what the execution herd does for 160 points... it comes in at a minimum of 1080 points for re-rolled attacks against a unit of your choice and that seems... expensive? The Hashut's Wrath Battalion I feel is a bit worse off than it was but its cheaper than the other ones for that extra command point / artifact and let's you get more use out of the Daemonsmith. On the other hand, I like the Blackshard Warhost a lot more now that the BSB is actually useful and that you want to take bigger blocs of Fireglaives. With the battalion, unit banners and the bsb its possible to get your Fireglaives and Ironsworn at bravery 9 pretty reliably now which is good (plus the bonuses for 10/20/30 models) - however the re-roll hit rolls of 1 in melee is probably going to be wasted since we get a lot of re-roll 1's in this army.
All-in-all I'm quite happy with these changes and look forward to fielding the Legion in AoS 2.0!