Imo, Schumann's large scale works don't "flow" properly...I don't know how to explain it. I can understand the dislike. First work I ever listened to was piano concerto and it sooooooooo repetitive and boring.
BUT, I love his piano cycles(set of miniatures) and variations. I believe that's where his talent was. Stuff like the Carnival, Dances of the league of David, Pieces from Childhood, symphonic etudes, ghostly variations, and romances etc...stuff like that are really amazing.