The models are fabulous. Alarielle is every bit as amazing as I hoped she would be based on the artwork and the fact that she is the first Incarnate released in Age of Sigmar (not counting Nagash as he is still technically an 8th Edition model). The scale is hard to accurately place but it does appear that she'll take up at least as much real estate as Nagash, and the model itself is incredibly detailed with a great pose. I can't understand the "her model is too detailed" complaints, isn't that what people want from models? Seems like a silly thing to chastise the designers for.
I think my favorite model is Drycha, so many little details and such an interesting take on what is presumably still a vengeful tree spirit (also, yay that they brought her back!) The beehives initially had me scratching my head but the high quality pictures eased my concerns there. Great model. The mini-Treemen, the Kurnoth Hunters, are cool for all the same reasons Treemen are; just miniaturized. I like the Revenants well enough but they aren't anything too special, though the Spite Revenants stand out a bit more than the Tree Revenants, I like the execution of the half-tree half-aelf concept. The Branchwych is a nice alternative to the Branchwraith and looks far more comfortable among Dryads, definitely fits in snugly.
Rules-wise this stuff is pretty darned strong aside from maybe the Revenants. Drycha is ridiculous for 280 points if the translated rules are anything to go by; she basically outputs more mortal wounds than Lord Kroak without needing to cast spells to do so, it's just automatic and impossible to defend against. She's not too difficult to kill with 10 Wounds, a 3+ save and no other defenses, but that permanent 9" move of hers means you need to deal with her quick or she'll murder scores of models in moments - damned nasty! Also, she has a 50% chance of getting 12 Attacks in close combat on any given turn when at full health, each of which is 4+ to-hit, 3+ to-wound, -1 Rend and 2 Damage. Yowza. If I'm not mistaken, she out-damages a Wrath of Khorne Bloodthirster overall assuming she gets close to numerous units...
The Revenants aren't anything special rules-wise considering the points costs, they just aren't that much better than Dryads to justify being nearly twice as expensive at identical unit sizes. The Spite Revenants are good for debuffing when combined with spawning Wyldwoods and Drycha's unique spell, while the Tree Revenants are incredibly mobile with their free teleportation (methinks they will be over-powered in objective grabbing games); definitely the latter unit seems the best way to go unless you go all in on Battleshock-manipulation.
Kurnoth Hunters are certainly interesting and are purpose built to go with Alarielle due to her healing abilities, five wounds each with a 4+ save plus the ability to choose to not move and only pile in 1" in a charge phase but re-roll all failed saves until the end of that turn (works in both players turns, get them in combat or wait for a charge then activate this, means you can perpetually give them a 4+ re-rollable save while they are locked in combat!) They are good in combat even if you take the Bows (you pick between Bows plus Vicious Claws, Greatswords, and Scythes) as each Hunter has a 50% chance to inflict a mortal wound on an enemy unit at the end of each combat phase. Not too shabby. The bows are actually something to consider because of that 30" range meaning they can easily single out characters and artillery. Very cool unit indeed.
The Branchwych is the close-combat oriented alternative to a Branchwraith and has a damaging unique spell rather than a summoning spell, she's cool. Alarielle though...what a beast. 5 attacks with her Beetle that do 5 damage....yowza, and she moves 16"! The way her Talon works is utterly brutal, make sure to do it after the Beetle attacks and provided you have her Command Ability activated and don't fail with her shooting attack Alarielle - assuming average rolls, rounding up where necessary - will kill Archaon in a single turn without any spells taken into account on either side. She's also purpose-built to serve units with multiple-wound models...like the Kurnoth Hunters. The "free" summoning she gets (it doesn't count as actual summoning) is sure to raise eyebrows too. Definitely on the level of Nagash and Archaon, albeit in different ways - both her and Drycha seem under-priced for their points as I don't honestly believe that Gordrakk should be 80 points more expensive than the Everqueen given their respective rules.
Semi-coherent spiel done....bring on the Sylvaneth pre-orders!