A very solid DLC!
The Story is pretty good and has some really fun and unique quests that work really well for the game. The Characters are some of the best in the game period. Olgierd is a very complex character and fits really well in a game like this, however I love Gaunter O'Dimm. He is my favourite character and the best villain in the entire game and i love how the game doesn't explain what he or it truly is. I will say though that the Ofier residents aren't all that interesting or really that present in the game. I like that there is another faction in the game, but i wish the game went into more detail with them or had some quests that involved them.
The Setting is kinda boring as it's pretty much more of Velen which in itself isn't bad but i think that the DLC could have had done its own thing or put a spin on what we've already seen. The only place that is unique in this DLC is the painted world which feels like an acid trip and I love it.
Visuals are the game as teh base game and so are the funny glitches here and there. The Art Direction is great cause its more of the base game, but again it doesn't do anything new or unique to really pull me in.
Sound and Audio are great with the soundtrack being more haunting especially with Gaunter's theme tune being one of the most chilling pieces in the entire game and the audio is just spot on.
In terms of Gameplay, its more of the same but with some tiny tweaks. The enchanting system is cool however i never found myself using it that much. I will say that one of the greatest improvements are the boss fights as they have been some of the best in the game so far and their attack patters were fun to learn. Apart from that there really isn't a whole new pile that the DLC offers but for what it lacks in the gameplay side of things it kind of makes up for in the story as it is so well done.
Overall, Heart of Stone is a good DLC and while there isn't a lot for gameplay, there is a really intriguing story that will have you hooked from start to finish!