Reddit says neither Lords nor Warriors is required; wait 4-6 base plays. Commenters call Lords excellent, balancing the slight Shadow lean with few extra rules. BGG rates it about 8.7.
Needs: Just the base game
Adds: Figures and rules for Elrond, Galadriel, Smeagol, Gothmog and the Balrog, alternate Gandalf, Witch-king and Mouth of Sauron, plus new Companions and action dice.
Fixes: Reddit commenters say it nudges the game's slight Shadow tilt back toward even (a claim another commenter disputes) and adds characters previously only on event cards.