Finished it. What an amazing dlc. Excellent story, full of well written characters. Challenging and unique boss battles. Fantastic quests. Some of them (wedding, haunted house) are amongst my RPG all time favourite.
The only disppointment for me were the new runewords. Most of them were pretty boring. Would have wished more creativity and variety.
And it showed me again that CDP's strenght is to write very "human" stories without this "chosen hero saves the world" bulls***** they unfortunately did with parts of Witcher 3. Let Bioware do these kind of power fantasy stories. The story of Hearts of Stone reminded me of the Bloody Baron questline and it was so much better than the Witcher 3 mainstory, just as Gaunter O'Dim was a far better written character than Eredin.
I also feel like I'm robbing CD Project Red. I needed 14 hours for 100% of the dlc and didn't play particulary slow. Way too much content for only 8,50€.
Oh and Geralt looks badass in the School of the Viper Set with a cape/hood mod:)