Bought the game after playing the excellent Hades.
The two games are quite similar, with only some differences (apart from the story, graphics and lore). In this game, we can use two different weapons from three classes (melee, ranged and shield) instead of one. The permanent upgrades feel a little irrelevant compared with Hades. Finally, the story is a little more convoluted, requiring that the player search and find the clues to piece what happened in the world.

Do not think of this as a typical DLC. This expansion adds an alternative for routes for the initial areas, with new bosses and weapons. In all, this doesn't even add a full hour of content.
However, if you follow the developer's social media you known that the DLCs are a way to continue to fund the game. The developers have not stopped working in the game, free of charge, for three years now.