Oh yess. Boss fights were better than the ones in the game, the story superb as usual, new equipment plus you get at least 10, 15 hours.
I'd get the season pass If i was you, 25 bucks for at least another 40, 50 hours. And the new DLC promises to be a completely new game.
If you get Hearts of Stone alone it's probably around 10 bucks. I got that special deal when I bought the game, both expansions for $15. In your case I'd go with the season pass.