A random thought first:
Season 2 tries to mention most places and important characters that the books mention, but the way they're bringing it together is really quite different to the books. All the right characters, all the right places (even with them simply being mentioned in dialogue for the fans, if they're not being shown), yet at times it's almost like a parallel universe in itself, because the connections from one situation to the next are handled so differently. That said, it did come together generally, yes.
I loved the costume design and they did a really good job with portraying Oxenfurt imo.
I just can't believe how negatively they portrayed Triss' impact on Ciri, or that they killed Eskel right at the start. Also how much fighting is happening at Kaer Morhen seems crazy to me, maybe mostly because this isn't so much a thing in The Witcher 3 (which is kinda fan fiction anyway, yes). I'm not far enough into the books to know if that amount of fighting at Kaer Morhen is happening in the books also, but I wouldn't have thought it is.
Generally how badly must Vesemir regret having taken in Ciri. Vesemir is still a loving grandfather so to say, but damn has he had bad luck with his castle and his boys ever since Ciri showed up.
I also find it a bit crazy how Geralt instantly knows all the clues and all the myths, like that about the deathless mother. Yes he's a centuries old hero, yes he's a legendary warrior and has traveled the continent more than almost anyone. Yet Yennefer is just as old as him but she was mostly unaware of the myth surrounding the deathless mother when in fact it was sorcerers and not witchers who had locked her up back in the day. I mean, that's a possible scenario that Geralt would instantly connect the dots, yes. But it seems like whenever the show needs to move the location to the next place that was mentioned in the books, someone just magically knows a clue that leads them to that place. After all the northern kingdoms are a huge area, how do these people keep randomly guessing the right spots to be at?
Especially in the books and the game Geralt often tries to seek guidance or information from others before being able to connect the dots, imo. He's obviously a good historian himself and knows a thing or too, but generally I feel like he's a bit too omniscient in some situations. Then again, how would they fit more background stuff into 8 episodes at the pace they're going.
Aside of some of the above mentioned things I really enjoyed the season too, but I already loved the way the first season set up the story. The acting in season 2 is much better and they obviously had more budget to work with. I'm intrigued by the introduction of the Wraiths of Mörhogg (The Wild Hunt), Emhyr's story, and the soon to be revealed team behind Rience - the fire magician (season 3 probably, I think book readers early into the second book will already know what the plot is here).