Single and multiplayer are as good as each other.

User Rating: 8.5 | The Lord of the Rings: The Return of the King PS2
This is is a must have for fans of the movie or books. The length of the game is quite short, taking me about ten hours to finish on my own in single player mode, and about 6-8 hours playing with a friend. There are great unlockables once you finish a level or the game. You can get interviews with the cast of the movie (and the voice actors). The game features cut scenes from the movie, which was a first when it was made (2003). There is some brutally hard gameplay to unlock once you've finished the game, where you have to survive 20 huge waves of enemies, who get harder and harder and harder. This game is maybe the best in the series of games, (having played and finished them all). The first in the series (The Fellowship of the Ring) is probably the weakest in terms of graphics, and this is probably the best. The controls are very easy to learn, as well. You can also unlock several different characters for gameplay. If you have unlocked everyone, you can play as Gandalf, Legolas, Aragorn, Gimli, Frodo, Sam, Merry, Pippin and Faramir. The boss battle are all hard and satisfying. You can fight Shelob, The Nine (The black riders), The King of the Dead, Gollum, and a annoyingly hard orc who stole Frodo's mithril vest.
All in all a solid action/adventure game, and a must have for LOTR fans.