Terrain generation for battlefields has been overhauled. Which now includes a bunch of new terrain features:
Bogs: Slow down units moving through them and prevent charges.
Forest: Slightly slows units, reduces incoming ranged damage, and has a chance to disrupt charges.
Rocks: Impassable, also blocks ranged attacks.
Fords: Most common river crossing, similar effect to bogs.
Hover ground that affects the fight for a card naming its effects in the top right.
Battlefield atmosphere
Rivers now have a nice flowing shader based on a pre-computed fluid sim.
Crows gather on open and wooded ground and scatter into the air when soldiers come near.
In autumn, leaves fall from the golden trees.
A new Ambience volume slider in the sound settings which controls ambient SFX.
The new battle AI
The battle AI has been completely overhauled.
The new AI makes use of the new battlefields. Taking strategic positions they decide to play defensively.
The new AI has a much better sense of where it's troops are, where your troops are, what formations to create, and in turn which tactics to employ.
Hopefully harder to cheese: Units should not chase cavalry that they will never catch. A defensive AI being plinked with ranged attacks will either bring their ranged troops forward if they outmatch you, or launch an attack after a few seconds.
Balance
A volley now reaches exactly as far as the archer shoots, instead of far beyond it. Longbowmen can no longer shell wall defenders from outside any reply: to volley a wall they must stand where the wall shoots back, and the wall's range bonus applies to volleys too, so defenders on the battlement out-range the attackers below.
Knights now have a 'lance' rather than a spear: 36 damage a hit, up from 32.
Shield walls now take extra damage from the rear and sides, rather than normal damage.
Battles
Formations ordered into a gap narrower than their line squeeze in to fit it, instead of piling half the men onto one point against the rocks.
Formation and shield wall drags show a chevron for the direction the men will face. Square walls mark all four faces; circles need none.
Large battles run far smoother, especially fully zoomed out.
Fixes
The hunted icon now disappears the moment you defeat the war party or raider band chasing you, and clicking a notification about something that no longer exists can no longer crash the game.
Bandits, including quest war bands, no longer spawn in lakes or rivers. Bands already stranded in water in an old save step ashore when you load it.
Leaving a battle for the main menu no longer keeps the abandoned campaign alive behind the scenes. It leaked memory and could crash the game later in the session, most often at the moment a peace was agreed.
Blood on wounded men now turns and bobs with the body instead of hanging still while they move.
Units draw in true north-to-south order. Cavalry used to render on top of any foot soldier standing south of them.
Orders that send men into a shield wall now show on the Space overlay like every other order.
Road work jobs: each robbed caravan was counted twice, and nothing marked which caravans counted. Robs now count once, and while the job is tracked the target faction's caravans carry the gold quest ring.
Retreating from a battle now leaves the enemy with the losses you inflicted, instead of restoring them to full strength. Wearing an army down over several fights now sticks.
A siege assault that is thrown back now costs the garrison the men you actually killed, rather than a fixed toll, so repeated storms grind the defenders down.
Notes for old saves
Saves from 0.3.4 load and carry on. The next field battle you fight simply uses the new maps and the new generals.