I saw parts of it - the stuff I remember:
The Taros campaign in the book is actually the *second* war for Taros - the Imperium returns to the planet after it's taken by the T'au (at this point it's a pretty well established world and relatively deep in T'au space) to reclaim it. By now Taros has been extensively mined - so extensively in fact that there's a series of massive caverns that wormhole the planet's crust, in which some of the campaign's engagements will take place (they wanted to include rules for more sci-fi themed settings). Another setting mentioned for campaign battles is in the upper stratosphere around a space elevator the T'au have constructed to transport the planet's mineral wealth into orbit.
There was talk of some familiar characters from the Taros Imperial Armour book returning, but not a huge amount of detail on any of the aircraft aside from discussing the general design philosophy of T'au aircraft - they're mid-ranged focused similar to the Imperials, and tend to have really high manoeuvrability but slightly slower speeds. As Aeronautica breaks down aircraft by their main weapon (i.e Thunderbolt & Thunderbolt Fury), the large degree of weapon modularity of the T'au aircraft means they've had to extend their serial numbers and split them into different profiles - so you'll have multiple Barracuda variants for the railgun/burst cannon/ion cannon for example. As the model previews have indicated, Taros also brings in more of the support aircraft that tend to be seconded to Guard Regiments - your Valkyries/Vendettas/Vultures.
That's about as much detail as I remember - they didn't show any images not already previewed on WarCom and didn't actually have the book on stream, but there was mention of perhaps having another preview closer to release so they can discuss the actual content in more detail.