Baba Yaga - The Temple of the Witch expands on the story of a Russian man who chases after the legend of Baba Yaga, a witch said to have killed his spouse. It fits pretty seamlessly with the main game, to a point I suspect it will take people who don't own this DLC out of the experience.

As for its quality, it's more of the main game. It's fun, the visuals are super enticing, but the level it offers is also home to the two worst puzzles in the entirety of RotR. So there's that.