Just a few things I've picked up since playing 1.19:
1) I've had crashes for the first time. This seems to happen right after a battle when I'm in cloth map mode and after the battle I zoom in.
2) AI heroes don't appear to use armor, at least in the games I played. They all had huge hitpoints and large attack numbers though.
3) The new select a unit dialog when casting a spell on a group of units is great. However, I cast flame blade, got the popup and selected my sovereign to cast it on. Then I cast flame blade again, but this time the popup didn't appear. It just cast flame blade on my sovereign again.
4) The AI has a group of units with a pioneer that just seems to stand on the border of my country. I know that it wants to claim a spot that has a resource next to my capital, but there is no accessible path to that spot, so it shouldn't try. They just sat on my border for ages and I got sick of looking at them and killed them.
5) I was at war with a faction, and while I'm fighting some of their armies, they send a lone hero through my territory to go claim a level 1 treasure on the other side of my empire. I picked him off quite easily.
6) Sometime you get hit by too many popups. I can get a city popup, a research tech popup, and a battle popup all at the same time.
7) I researched adventuring (or whatever it is to reveal level 2 treasures) and no level 2 treasures appeared any where that I could see. However a few level 3s were around.
8) I've mentioned this before in a post, but when you choose a distant location for a unit to move to, it doesn't seem to calculate the quickest path. The unit will tend to move through a forest rather than go around it.
9) The last one probably isn't an issue, but I thought I'd mention it anyway. I was playing the Expanded Factions mod, which I noticed Heavenfall said isn't compatible with this version. However, I attacked the Angels and was advancing into their territory and I noticed that they had two pioneers in the ocean. Probably something to do with the mod.
Thats all I've noticed for now. However I do think the tech tree needs to be thought out a bit differently or armor needs tweaking. It seems too easy to get to leather armor quite quickly, which is overpowering.