I have around 2000 hours in EU4 and probably around the same for EU3 before that. I am also familiar with Victoria 2 and 3, Hearts of Iron, Crusader Kings 2 and 3, and Stellaris when it comes to PDX games.
I have only started playing the game after the release of 1.3, so I cannot comment on the state of the game before that. While I haven't played much yet, I can already tell that EU5's direction is exactly what I always wanted from this game.
While I did have a lot of fun with EU4, it did feel quite "gamey" with its mana-based mechanics, I thought the trade system was a step back from EU3, and playing tall didn't feel satisfying. The only thing you can do in EU4 is paint the whole map your own colour. Once you are the undisputed #1 Great Power, all challenge is gone. The rest of the game is just dedicated to painting the map for the sake of it. I never finished a world conquest, simply because there was no challenge anymore once I eliminated the last big nation that could match my strength. It's just tedious micromanaging of armies at that point, conquering province after province without any resistance, just watching the map turn into you
EU4 feels like a very well made, well balanced board game, whereas EU5 aims at being a more in-depth simulation. It is funny, the thing that some other players complain about is exactly what I love about EU5.
When I play Victoria, I love the deep production, trade, population and politics systems, but I miss the map painting of EU4. CK3 is essentially a story generator in a similar way to Rimworld. I love the RPG aspects and the story arcs, but I miss the depth of trade/production of Vicky as well as the map painting of EU4.
EU5 incorporates all of these systems into a unified whole, making it the deepest, most complex historical grand strategy simulation to date. Personally, this is what I always wanted from the EU series. I don't just want to paint the map. I love being able to micromanage my production and trade. The production and trade system of Victoria 3 alone was enough for me to fall in love with that game. Now, I get to have my cake and eat it too. All of the best features of past PDX games combined into one game. I love the ambition and the direction it takes.
EU5 feels way more realistic. What always bothered me about EU4, especially once I got good at the game, is that I always felt like I was exploiting game mechanics rather than playing a realistic historical simulation. For example, let's say I start as England in EU4: I could just abandon my French territories and play "as intended" on my little island and colonize the Americas. But if you know how to beat France early on, it is kind of hard to resist the temptation. Then you immediately have France as your junior partner, your biggest rival is gone immediately, and you just proceed to steamroll everybody else on the map and paint everything in your colour. EU4 gives you lots of free cores via missions and generally makes it extremely easy for the player to conquer everything in a very short amount of time. Once you get good, it's more like a puzzle game that scratches the speedrunning itch. How many countries can I conquer at once? How quickly can I paint the whole map by using all the game mechanics at my disposal optimally, minmaxing as hard as I can? While this can be fun, it's also a very narrow axis, and it's not really what I look for in a grand strategy game. And I say that as someone who generally loves min-maxing and speed running in other games.
EU5 slows the pace way down. You cannot as easily conquer everything everywhere in a heartbeat. You have to wait for parliament debates to fabricate a casus belli early on, you do not get free CBs handed to you like candy, and keeping your country stable and integrated also takes more effort. EU5 makes playing tall really viable and fun, whereas in EU4, this always felt lackluster. The optimal way of playing EU4 was always to blob as fast as possible. Some people seem to find this boring. They complain that they have "nothing to do" and have to wait around for too long until they can conquer something again. I feel the opposite. I love that finally it feels like I have something to do OUTSIDE of just conquering everyone around me as quickly as possible.
TLDR:
If what you want out of EU is a deep historical sandbox simulation that has everything from production, trade, population, warfare, diplomacy etc., you will already love EU5, and I'm willing to bet it's only going to get better from here.
If you want a speedier experience, just painting the map with simpler, more board game like game mechanics, much like a glorified version of "Risk", you will prefer EU4, and EU5 may feel slow, tedious, and boring to you. At least, this is what I've been reading a lot from some players coming from EU4.
For me, I couldn't be happier with the direction PDX has taken with this game. I do not agree that it feels bloated. I wish all of this complexity had already been there in the EU games of the past, and I'm excited to see how the game will develop over the next couple of years.
