I'm gonna start this by saying I'm probably not part of eu4's main target demographic,and that you might enjoy the game despite those issues,but I feel like if I was asked by a friend about eu4 I couldn't reccomend it.
The big main issues I have are 3:AI,RNG and complexity.
I'm not a top player so I can't do a proper,in depth look on the functions of the AI in the game.That said eu4 has an issue that's plaguing a lot of strategy games,the AI,especially allied one,is simply just bad.Focusing on the friendly side of it,I can bet all i have that no matter who you get off the street and on a chair to play this,they won't do as badly as an ally in game.From things like rushing into a bigger army for no reason,to moving at the last second of a siege nullifying all that time spent to not even joining a war because it entered a debt that would put the United States to shame.It's simply frustrating to see the AI do anything in the game.
But you know what,I can forgive that,after all its best to do something yourself rather than having someone else do it.What I can't forgive is the RNG.Now,I will fully admit that when it comes to RNG or anything luck related I can act worse than a 9 year old who got his tablet taken in public so take this with a grain of salt.I never enjoyed difficulty or plans that require any amount of dice throwing,I know its supposed to help variety,but RNG shouldn't feel like it's there to punish you for no reason.The classic example of this is sieges,instead of making a system around starving the enemy or sieging it,you are left with a dice and modifiers,if they go at certain numbers,you increase the modifier,if you reach 1,your army gets wounded (disease) and if you reach a high number,you break a wall to siege.This leads to having a final fort or even anything not be a problem of maneuver or combat,rather an issue of time,bad luck leading to waiting around hoping that this roll is good.I want to believe this could create tense moments,where you hope to finish that fort before an enemy army comes,fleeing but still having land captured but sadly I never felt that way.There's also random events that are basically choose whatever you want to lose,they never felt like issues with the state,economy or whatever and rather just felt like a cheap way to have difficulty.
The third thing,complexity,is a much more objective thing so this is something you don't have to pay attention to if you don't mind simpler mechanics,which is 100% fair to enjoy.I usually like game that take time to learn,that have depth and complexity to have you to think more and be engaged with plans.At first,eu4 seemed promising,the ui itself looked like it had a lot of stuff going on and people said its hard to understand,so I hopped in and played enough for some people to consider it a time waste.Sadly,the more I played the more I felt like a lot of mechanics are never engaging,they are there,they affect the game,but they always felt fire and forget,you don't pay attention to them and if you do,its mostly bigger number means better.Another issue is that said features feel like they are added more and more,creating a game wide as an ocean but deep as a puddle.
Of course,aside from these i have other issues,like achievements being unfair or absolutely frustrating,the game never modelling an empire collapse properly but these are the big 3 issues that I feel define my unpleasant view of the game.
Outside of just the game,it feels like I wouldn't recommend the game due to Paradox itself too.They have been known of bad or barebones releases that get fixed years later and controversial dlc policies,which are visible in eu4,from the bad release of Leviathan to locking basic game mechanics to dlc I wouldn't trust Paradox on eu4 or on any future projects.

I'm gonna start this by saying I'm probably not part of eu4's main target demographic,and that you might enjoy the game despite those issues,but I feel like if I was asked by a friend about eu4 I couldn't reccomend it. The big main issues I have are 3:AI,RNG and complexity. I'm not a top player so I can't do a proper,in depth look on the functions of the AI in the game.That said eu4 has an issue that's plaguing a lot of strategy games,the AI,especially allied one,is simply just bad.Focusing on the friendly side of it,I can bet all i have that no matter who you get off the street and on a chair to play this,they won't do as badly as an ally in game.From things like rushing into a bigger army for no reason,to moving at the last second of a siege nullifying all that time spent to not even joining a war because it entered a debt that would put the United States to shame.It's simply frustrating to see the AI do anything in the game. But you know what,I can forgive that,after all its best to do something yourself rather than having someone else do it.What I can't forgive is the RNG.Now,I will fully admit that when it comes to RNG or anything luck related I can act worse than a 9 year old who got his tablet taken in public so take this with a grain of salt.I never enjoyed difficulty or plans that require any amount of dice throwing,I know its supposed to help variety,but RNG shouldn't feel like it's there to punish you for no reason.The classic example of this is sieges,instead of making a system around starving the enemy or sieging it,you are left with a dice and modifiers,if they go at certain numbers,you increase the modifier,if you reach 1,your army gets wounded (disease) and if you reach a high number,you break a wall to siege.This leads to having a final fort or even anything not be a problem of maneuver or combat,rather an issue of time,bad luck leading to waiting around hoping that this roll is good.I want to believe this could create tense moments,where you hope to finish that fort before an enemy army comes,fleeing but still having land captured but sadly I never felt that way.There's also random events that are basically choose whatever you want to lose,they never felt like issues with the state,economy or whatever and rather just felt like a cheap way to have difficulty. The third thing,complexity,is a much more objective thing so this is something you don't have to pay attention to if you don't mind simpler mechanics,which is 100% fair to enjoy.I usually like game that take time to learn,that have depth and complexity to have you to think more and be engaged with plans.At first,eu4 seemed promising,the ui itself looked like it had a lot of stuff going on and people said its hard to understand,so I hopped in and played enough for some people to consider it a time waste.Sadly,the more I played the more I felt like a lot of mechanics are never engaging,they are there,they affect the game,but they always felt fire and forget,you don't pay attention to them and if you do,its mostly bigger number means better.Another issue is that said features feel like they are added more and more,creating a game wide as an ocean but deep as a puddle. Of course,aside from these i have other issues,like achievements being unfair or absolutely frustrating,the game never modelling an empire collapse properly but these are the big 3 issues that I feel define my unpleasant view of the game. Outside of just the game,it feels like I wouldn't recommend the game due to Paradox itself too.They have been known of bad or barebones releases that get fixed years later and controversial dlc policies,which are visible in eu4,from the bad release of Leviathan to locking basic game mechanics to dlc I wouldn't trust Paradox on eu4 or on any future projects.