I like the IDEA of the House Elves subplot (pointing out that the glorious wizarding world isn't perfect and is basically involved in instutitionalized slavery, and having a character decide that's wrong and stand up against it), but it wasn't executed well in part because it went nowhere but also because the other main characters didn't care and so it made THEM look like complete tools while trying to portray it as the opposite, that Hermione's got some silly notion in her head that they have to indulge but isn't really important.

That said, it was at least more interesting to me than "Harry gets involved in a competition where he's given the answers at every turn and so doesn't actually have to do much in order to win, all in a complex plot to make him touch a portkey to get him into Voldemoort's clutches, when one of the main badguys involved in the plot was masquerading as a trusted teacher and could have had him touch one during a frivolous detention or something." (Well, okay, at least that plot had a few entertaining action sequences out of it).