I managed to play a game before the fixes; I didn't notice any critical bugs, except for that minor bug with the Archon's scythe, which has already been fixed, and the black space under the Knight when he dies.
Gameplay-wise, the Swamp Knights and the Undead Warriors are overpowered, without a doubt. Orson will dominate in the early stages of the map, especially in battles with neutrals.
Added 11 minutes later
I'll add: I spent most of the Town Energy on Warriors and Sisters (because of sieges), and I gathered a decent number of them. With the fix, as I understand it, this strategy won't work anymore; all the Town Energy goes only to skeletons.
Regarding Naadir's flies, I didn't feel a significant gameplay difference, although I admit that sometimes their size saved them from larger units. It's quite possible that I didn't fully appreciate this approach, as I focused on the Undead Warriors.
The Undead Warriors and their upgrades are nothing more than the essence of necromancy!
I haven't played yet, only tested necromancy; I'll probably play as Orson.
This should be a battle of titans: Orson with the Undead Warriors, Groll with the Gnomish Spellcasters who fire magic arrows, and you can also take Haggeesh; they only have fire elementals with retaliatory attacks, but it's still cool