Like the post above, the less competitive direction taken for Brawl caused some fans to dislike it (tripping, slower gameplay) on top of poor character balance (Meta Knight being broken, Ice Climbers also being pretty OP with chaingrabs, and Ganondorf being unviable).
While these are complaints, Brawl is the most nostalgic entry for me with the the Dojo, Sonic’s addition, introduction to Stage Builder, SSE (Ultimate is better now with 8 player smash and roster and stage selection more than twice as big as Brawl’s, but Brawl is special to me).