First, the UI improvements:
During the Movement phase, there is now a "Next Unit" dialog in the lower left similar to the one used to cycle through artillery units during Artillery Defensive Fire.
Garrisons are more clearly highlighted
Under Settings, players can choose to use the original stylized font on markers if they prefer
Also under Settings, players can choose to skip the Tactics Cards selection when playing both sides of a combat. The result will always be a 0 modifier to the attack.
Previously, the game would highlight potential moves for the Americans that would move units outside of Bemis heights before Gates was released. This has been fixed.
Some text corrections were made in the close combat tutorials.
The AI should now be much better at protecting artillery and leaders. During an advance after combat, the AI won't leave an artillery unit behind if it's possible to keep a combat unit with it. Also, artillery will normally try to move into a hex with a friendly combat unit if alone. If that's not possible, then the artillery will check to see if it's in danger of being attacked - if it is, then it will try to move to a hex that cannot be attacked. If that's not possible, then it will remain where it is and fight. There are exceptions to these actions, but this should be the behavior you see generally.
von Riedesel has had his AI modified to make him less likely to move out ahead of his German troops.