I have now hit 2k hours on the game.
Here is my opinion.
The game is fun with mods, but overall the vanilla is good. The minor nations are horribly unfun to play and even to try and play them leads to you wanting to not. Major nations such as Germany and japan are a great start of your time in HOI4.
The metas and balance changes are sometimes questionable but overall you can do a lot of things but in reality there are good and bad and not a lot of in between balanced stuff. IE, subs are still the best choice, Infantry is still better than tanks, fighters and cas are the best for the air.
The best mods for this game are Road to 56, Kaiserredux, and Thousand Week Reich. TNO being a little too edgy for me.

My complaints:
The supply system and spy system are still not very impactful, though the meta of using German spies for German Intel is good and making a big civ count to easily make supply works. I feel as if both of these systems do not work as intended. For spies, you really can only create collaborations, the boosting of ideology doesn't start a civil war or anything and the ai doesn't fight back your influence by banning your ideology so it just feels weird when Adolf is allowing communism to spread. Too comes supply being weird and unbalanced for some countries, this adds to my previous point of minor nations being unplayable because you realistically cant play them due to supply problems, limited building slots, and manpower. Which makes sense, but also it would be cool if you could form more and core stuff so you can expand and have a further drawn out war in to later dates.
Secondly, wars and minor wars. This game severely needs a rework to the peace out options, if you are winning 90% or 100% of your battles and want a minor peace out with just taking a state off of someone and then coring it. You should be able to, just so WW2 or WW3 doesn't start because of Columbia or Iraq. Which once again doesn't make any sense. WW2 should only proc at the war with Poland, and only Poland. Too can be said about the Benelux, it makes no sense how Germany is allowed to take Belgium and the Netherlands at the start of the game.
Third, AI. The ai is no longer able to beat me, and i know this sounds stupid but its true. If I play a major nation build a decent air force and infantry army and dont play stupid I will never lose a game of hearts of iron 4. Which is why my fix would be this, Germany needs to have a blitzkrieg bonus of 25% buff to attack too needs to be done for japan. Both of these nations absolutely raped the world during their times of horror. So to downplay their abilities seems a bit not only stupid but unfun. I would be so much more interested in HOI4 if the AI could beat me on my misplays. Also an addition to the AI code I would add is this, dont attack until green bubble appears, make separate tank generals that are placed in one or two areas to assist infantry, place air force on top production so air wars are important. And make more ships to harass the allies. Again this adds to japans code too, they were winning all of their battles before midway irl so to simulate this have both japan and the germans be scary. Also add a buff for the allies near the end of the war, something like liberating europe so they actually do something. Again it goes to the idea of the ai not simulating reality.

HOI4 should play like the Axis does well at the start, they lose their buffs, the war draws on, both the allies and cominterm gain buffs themselves, the axis then become desperate for manpower, the war the goes to the benefit of the allies and cominterm. Then the axis collapses once their holes in their defense are attacked (ITALY). Then the game ends in 1945.

How the game plays for me; The axis and allies have the same amount, I create an airforce and good infantry. The axis is not able to beat me. The war draws on to 1940. When 1940 hits I kill them. The game is over. You see the problem here.

Thats all, good game still.

I have now hit 2k hours on the game. Here is my opinion. The game is fun with mods, but overall the vanilla is good. The minor nations are horribly unfun to play and even to try and play them leads to you wanting to not. Major nations such as Germany and japan are a great start of your time in HOI4. The metas and balance changes are sometimes questionable but overall you can do a lot of things but in reality there are good and bad and not a lot of in between balanced stuff. IE, subs are still the best choice, Infantry is still better than tanks, fighters and cas are the best for the air. The best mods for this game are Road to 56, Kaiserredux, and Thousand Week Reich. TNO being a little too edgy for me. My complaints: The supply system and spy system are still not very impactful, though the meta of using German spies for German Intel is good and making a big civ count to easily make supply works. I feel as if both of these systems do not work as intended. For spies, you really can only create collaborations, the boosting of ideology doesn't start a civil war or anything and the ai doesn't fight back your influence by banning your ideology so it just feels weird when Adolf is allowing communism to spread. Too comes supply being weird and unbalanced for some countries, this adds to my previous point of minor nations being unplayable because you realistically cant play them due to supply problems, limited building slots, and manpower. Which makes sense, but also it would be cool if you could form more and core stuff so you can expand and have a further drawn out war in to later dates. Secondly, wars and minor wars. This game severely needs a rework to the peace out options, if you are winning 90% or 100% of your battles and want a minor peace out with just taking a state off of someone and then coring it. You should be able to, just so WW2 or WW3 doesn't start because of Columbia or Iraq. Which once again doesn't make any sense. WW2 should only proc at the war with Poland, and only Poland. Too can be said about the Benelux, it makes no sense how Germany is allowed to take Belgium and the Netherlands at the start of the game. Third, AI. The ai is no longer able to beat me, and i know this sounds stupid but its true. If I play a major nation build a decent air force and infantry army and dont play stupid I will never lose a game of hearts of iron 4. Which is why my fix would be this, Germany needs to have a blitzkrieg bonus of 25% buff to attack too needs to be done for japan. Both of these nations absolutely raped the world during their times of horror. So to downplay their abilities seems a bit not only stupid but unfun. I would be so much more interested in HOI4 if the AI could beat me on my misplays. Also an addition to the AI code I would add is this, dont attack until green bubble appears, make separate tank generals that are placed in one or two areas to assist infantry, place air force on top production so air wars are important. And make more ships to harass the allies. Again this adds to japans code too, they were winning all of their battles before midway irl so to simulate this have both japan and the germans be scary. Also add a buff for the allies near the end of the war, something like liberating europe so they actually do something. Again it goes to the idea of the ai not simulating reality. HOI4 should play like the Axis does well at the start, they lose their buffs, the war draws on, both the allies and cominterm gain buffs themselves, the axis then become desperate for manpower, the war the goes to the benefit of the allies and cominterm. Then the axis collapses once their holes in their defense are attacked (ITALY). Then the game ends in 1945. How the game plays for me; The axis and allies have the same amount, I create an airforce and good infantry. The axis is not able to beat me. The war draws on to 1940. When 1940 hits I kill them. The game is over. You see the problem here. Thats all, good game still.