It just... didn't work for me...
It was a major disappointment, and possibly my biggest case of buying into the hype and pre-purchasing rather than just wait and see. It seemed like the dream game: a mix between the classic sci-fi 4x tropes, the Paradox grand strategy approach to borders and war diplomacy, the galactic scale and detail level of Distant Worlds, all with gorgeous UI and graphics. Sadly, it fell flat very quick for me. And nothing due to one big thing, it's just a number of things adding up. Like some of the micromanagement feeling silly at the game's scale (the planetary grid for buildings), the battles (seemingly) consisting about spamming more ships, an underwhelming economic/resource model, and, I guess, the major lack of personality of the setting. I love the idea of traits, I love the idea of pre-existing Fallen Empires, but do the rest of the empires really all had to start at the same time? And with no history? There's something lacking there where I wish they'd have taken a page from Dwarf Fortress and generated those galaxies from the ground up by simulating a history and giving you access to records describing that history. Asymmetry, historical ties and past are one of the things that makes every single nation/character interesting to play in EU/CK. That's missing here, sadly.
So personally, I enjoy more Star Ruler 2 and Distant Worlds for pausable real-time, and Endless Space 2 for the more traditional turn-based approach. None has everything I'd want, but they each satisfy a specific craving where Stellaris just feels lacking. Still. at the end of the day, it's a fine strategy game, it's absolutely gorgeous, and it'll be updated for a good while, so if you find it at a discount for black friday or winter sales, there's little risk in going for it. And if it resonates with you, you'll be playing it for a long time.