I'm still on board with the overall direction of warfare in this game, as the agency we've lost at the tactical level has been made up for in the economic gameplay which is miles better than what Vicky 2 offered. Additionally, much of the micro of armies from other Paradox games has been removed, like patrolling your stacks across multiple theaters to make sure the enemy doesn't pounce on them out of nowhere, or needing to go deal with the enemy's units that have decided to go siege your holdings in Siberia 5000 miles away, so that's good.
That said, there's a ton of pain points with warfare as it exists right now. I don't think any of these are fatal and most could be fixed with a few tweaks, but some of these really need to be high-priority fixes because they're killing an otherwise pretty fun game.
- The amount of troops engaging in a battle, and the rate of frontline advances in general, both need to be looked at. If I as the USA have 150 units to Mexico's 10, and the frontline is thousands of miles long, I should not be losing battles over and over because my general refuses to send more than 5 battalions into combat at a time, in battles that end up lasting over a month. What the hell are the rest of my guys doing???
- Fronts merging or new fronts opening are both really janky. Sometimes it means the general gets deassigned from the front and your troops teleport home. Other times it can mean all the enemy troops are in a tiny pocket and the main front proceeds 100x faster.
- A general dying of old age during combat should not mean all their troops teleport home, especially when there's penalties for retiring generals.
- Being in one war should not lock you out of starting other wars. The EU4 devs realized that getting locked out of declaring war from regencies is really, really not fun and they eventually effectively removed it. I exceeded the infamy cap as the USA which resulted in Austria(?) declaring war on me. They ended up being completely irrelevant since their army was smaller than mine and they couldn't even make it to the Western hemisphere since my navy was so big, but they still wrecked my plans because they locked me out from declaring war on other nations. I waited for years but they never wanted to even make a white peace since their gold reserves were high, and the passive war enthusiasm loss doesn't ever go negative. I tried invading them, but my dumb generals tried doing D-Day with only 5 battalions of their 100+ battalion force. I was effectively completely paralyzed in the most stupid way possible.
- Being forced to put all your wargoals before the war breaks out is completely ahistorical and ridiculous. It's even worse when the enemy surrenders without a fight, because you get the infamy gain up-front, and are only partially refunded when the enemy gives up.
- There should be a way to force a war, i.e. to not let the enemy "surrender" without giving up ALL of the wargoals instead of just the first one. The Mexican Cession is taking me decades because Mexico keeps surrendering one state per cycle and getting a 5-year truce every time.