Pure Fan Service
I love these LotR extended editions. They give more depth to already spectacular movies, and they allow fans of the books to see scenes that the general movie going audience likely wouldn't understand or care for. Since I've already given a review of the movie, this will focus on the new scenes.
Many scenes that were already in the movie have been extended as well, but for the most part, don't really bring anything new. The first new scene has Sam and Frodo trekking through Emyn Muil, and it brings out the never-say-die attitude in Sam once again. Roast chicken, anyone? Massacre at the Fords of Isen has Eomer and his men searching through bodies at the Fords, looking for the body of Theodred. Any scene with Eomer is ok with me. Treebeard actually sings about the Entwives, the long lost mates of the Ents. It's a beautiful scene, showing the vastness of Fangorn, while exploring the history of Middle-earth as well. Gandalf briefly mentions Numenor to Aragorn, which is pure fan service. Numenor was an island of mighty kings, from which Aragorn is descended. Ent Draft features Merry and Pippin growing taller from this magical water, and then being captured by Old Man Willow. This actually happened in the Fellowship of the Ring, and they were saved by Tom Bombadil, not Treebeard. Who is Tom Bombadil? Why, he's Tom Bombadil, of course.
The Funeral of Theodred is a great new scene, in which Eowyn sings a song in the language of the Rohirrim, which name evades me at the moment. Brego is a new scene where Aragorn tames his horse. I guess he doesn't come out of nowhere after all. Brego is actually the son of Eorl (Forth Eorlingas!), and he finished building the hall at Meduseld. The Ring of Barahir shows Grima telling Saruman of Aragorn and the ring he wore. This has been a heirloom since the wars of the first age. One particularly funny scene has Aragorn telling Eowyn how old he really is. The final scens kind of throw of the pace and impact of the ending, but they're still welcome. One has Gimli and Legolas tallying up their votes, one has Sam and Frodo departing from Osgiliath and Faramir, but my favorite is all of the retreating Uruk-hai running into the forest and being devoured by the Ents and Huorns.
The new scenes are great, and so are the special features. There is one DVD devoted entirely to Gollum. This is a must buy for any LotR fan.