EU4 is maybe my favorite game of all time and definitely my favorite strategy game.
EU5 felt good at first but as you actually begin to understand the game, there are a lot of shortcomings and unsatisfying mechanics, not to mention all the bugs. The flavor is largely hard to access so different nations feel too similar flavor wise. Yet, it is probably one of the best Paradox launches, for what little that is worth.
My biggest issue is what they've shown of their post release support and development processes. I think they're cowboys without a solid plan, without a great understanding of their own systems, most definitely without the kind of manual and automated testing support this kind of game needs, too small a team for their ambition, and too much ego by Johan. At the state it was at during release, I thought it could be decent in six months. After observing how they operated post release, I think it will be two to three years, if ever.
Don't get me wrong, you can still mostly play campaigns, especially European ones, and do mostly okay. There is a lot of tedium and QoL and bugs to deal with and if you happen to get hit by a game breaking big, it's super deflating because It's easily double or triple the length of an EU4 campaign.