I don't think Return of the King was butchered, but I think that it definitely lies in the shadows of the other two movies just because they were so good and that Return of the King suffered badly from third film syndrome. The Fellowship is the wonderful start to the adventure that is so exciting and unbelievable that none of the party really has grasped what it is they've embarked on, The Two Towers is the confrontation of the realism of the situation, a multitude of storylines and a smurfing epic battle. I think that by the time Return of the King was done with, everyone just wanted to watch it to get it over with.

But I also have only read Return of the King once and Fellowship of the Ring and The Two Towers much more, so I could be misremembering about potential butcherings.