I've noticed some small dialogue changes, and someone attacked me on sight in retaliation for having killed Siegfried in my Witcher/neutral playthrough of the last game.

It's a lot more subtle than Mass Effect 2, but I think subtlety is one of CDPR's strengths.

There are some instances where it does seem to have an effect in terms of the dialogue. But there are other where they clearly don't. For example, I believe if you killed Adda in the first game they will mention that. But on the other hand, regardless of what faction you chose (and/or neutral) in the first game, it will say you helped a Scoia'tel uprising. So it's hit or miss.

But as far as I can tell there are no quests based on decisions you made in TW1.

First thing I noticed is that Foltest mentioned that Adda and Radovid are married. Actually, only thing I've noticed so far.

If you don't import, then Foltest talks about how Adda died when you are by the Balista. If you import and she lived, then he thanks you for saving her I think. The dialog is definitely different based on the major choices.

It would also seem that some of the content doesn't adapt to your actions in the previous game. For example,I saved Adda in the save I imported, but a book that I bought in Chapter 1 states that Adda was killed.

Ah.. I think I got this as well. Pretty sure I saved Adda in TW1, didn't pay attention to Foltest so didn't hear the part with him thanking me, but read somewhere in my journal that Adda was killed. I just assumed she was killed by someone else. (I think there was something about her turning into a Striga again?)

Adda died before the events of the first game, but came back to life as a striga. I think that's what they're referring to.

At the village outside Flotsam there is a man telling a story about Adda and the Stiga. I lifted the curse in TW 1, so that was reflected in the story.

By the way, Adda's mother was also called Adda. She died giving birth to her daughter.

I think there was another Adda, too. It's all complicated, so the internet can explain it for everyone: http://witcher.wikia.com/wiki/Adda_the_White

Ahh

Ok, thanks guys, maybe I'll just have to pay closer attention to it, or perhaps after I'm done with this play through, when I start a new game see what the differences may be to truly compare, as I only have the one save with my decisions based on the Flaming Rose Ending.

I've managed to find the book I was referring to in my last post - it's called "The Temerian Royal Dynasty" and the last line reads "Unfortunately it returned after a few years and the witcher was forced to slay the monster." As I mentioned in the last post, in my W1 playthrough, I actually saved Adda...

Yes, there are indeed two Addas, the first was Adda's (the Striga) mother, but she died of, well, "natural causes" (in case some of you haven't read the books).

That means the one that was killed by a Witcher couldn't have been Adda's mum, and it would have referred to Princess Adda that Geralt lifted the curse from. (Which was what some of us did in TW1) So the journal entry was either bugged, or the curse reverted (Geralt did advice King Foltest to continually do certain things even if the curse was lifted, so it seems like a relapse was possible) and he was forced to kill her; or it could even be intentional - books doesn't always produce the true account of things. Dandelion's entires in your journal certainly shows that writers tend to embellish and even make up things that were not entirely true.

About Siegfried :

I really don't remember killing him following the witcher path but the game assumes I did.

I have read the same from other players so I'm wondering if my memory is just terrible or if there is some issue with the save import* ?
(* i.e.the game assumes Siegfried is dead if you chose the neutral path, whether you spared him or not)