Meeple Mountain calls it one of the two best Castles expansions but notes hefty rules overhead and no player aid. Punchboard calls it big and 'really well done'.
Needs: Just the base game
Adds: A vineyard board on each duchy and a tile rack. You place double-hex tiles on it, and more tiles of the same type score more victory points.
Fixes: No base-game flaw is cited by reviewers; it adds a second set of tile-placement goals rather than fixing something.