From the reviews I've read - nothing. It's primarily B/X with some AD&D houserules layered over it (essentially retreading the ground of OSE Advanced). I don't get the idea that it brings anything substantial to the table beyond what you'd see in OSE/Dolmenwood, Shadowdark, etc.
Primarily, it's a means for the author to get away from Labyrinth Lord because he has a beef with that designer. So I guess if you like Gillespie's megadungeons (like Barrowmaze), you might want this for future releases.
One fan reviewer spoke at length how revolutionary it was to have "ready-made equipment packs" for quick character creation, so I guess you've got that. (Provided you didn't want to use 5e or Castles and Crusades, or other games that have been doing that for a decade or more.)