The new expansion is a huge amount of fun for someone like me who's sank way too many hours and knows how virtually every game will play out; the "meta" (if you can even call it that?) is completely new and the world tends to develop very differently than what I'm used to. I suspect this has a lot to do with the new traits system giving every ruler their own AI personality. Another huge, underrated change/fix was that the AI no longer increases autonomy in provinces they want to make states. It sounds like nothing, but beforehand every single province the AI conquered would instantly be set to 100% autonomy. Basically, it meant that the AI took 100+ years before the land they conquered actually made them stronger. Completely ruined the AI and could make the game feel easier than it should have.
Definitely needs a patch or two to smooth things out though, right now there's a lot of silly stuff. I've only played one game and already noticed way too much "fun", here's a couple examples:
* Apparently being a single institution ahead allowed the Ottomans to make the entire Mamluk Sultanate a protectorate. This turned the Mamluks into a "nogovernment", stalled Ottoman expansion south, and naturally had a huge amount of liberty desire.
* If you release a trading city and aren't sufficiently large, that trading city will instantly rival you. Woops.
The one intentional feature of this patch that I'm not sold on is how forts work now. My fears when this was announced were that mountain forts would be gamebreakingly strong, and that's exactly what they are. I've watched the Ottomans try to invade Qara Qoyunlu four times now and only once did they manage to siege down a mountain fort before being repelled. I certainly wanted forts to be stronger, but this is going way too far. You even take the river crossing penalty if the relieving army crosses a river beforehand!
The new tech system is cool but the numbers and spawn locations need serious work. Instead of tech groups, you're now either "European" "Near Europe" or "Backwater". As far as I can tell, institutions spread very slowly compared to the penalty they give. China is already starting to tick up towards 200% tech cost fifty years after gamestart as the Enlightenment has barely made its way out of Anatolia. Unless something I missed causes institutional spread to increase massively, you can basically expect to have pre-RoM Native American tech costs in the east for most of the game.