They've included extra material from other Tolkien works in the 3 movies.
As some of you may know, I'm a Star Wars fan. A huge one. Have a look at my site and you'll see

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Over the years, many people said George Lucas was all about cash. Many of them were 'Rings' fans who put their 'holy' Peter Jackson on a pedestal. 'PJ' will never sell out, they said.
Oh, but he did now. (to my amusement....I can have my revenge now and strike back with their Lucas comments....wich now apply to Jackson)
Don't get me wrong, I love 'Rings'. I adore it. The books that is. In fact, HEROQUEST got me reading it! I started with HQ in late 90/early 91, and later that year I read 'Rings' for the first time (immediately followed by the Hobbit)
The version I created in my own head when I read it is still the best. The only Orcs I had ever seen were the HQ Orcs and I had no idea how a Hobbit looked! The books are so well written I could easily imagine everything. I am still VERY happy I read the books BEFORE I saw the movies.
Yes, then came the movies. I had seen the animated movies (the Hobbit and Return of the King from Rankin/Bass and Lord of the Rings from Ralph Bakshi (both NOT as bad as many people want you to believe)) but everyone looked forward to the live action flicks.
To be honest: they're great. I hated the fact they cut so much from 'Fellowship' (my favorite of the 3) but it was a well made movie. Still, it came nowhere near my 'own version': the book was/is soooooooooooooooo much better.
Now, there's The Hobbit. I liked the book, but Rings was way better. At first, there were gonna be 2 parts. Then, it became 3. If this isn't about the cash then I'm JarJar Binks.
PS: another thing I hate about the movies is the fact some fans are always saying it's 'so much better than US movies' and 'it's a New Zealand movie and not a 'Yankie' flick'.
Well;
-the movie is based on a novel written in by an ENGLISHMAN
-the movie was financed by an AMERICAN studio (NewLine)
-the movie stars AMERICAN (Wood, Mortensen, Astin, Tyler) and BRITISH (Lee, McKellen, Davies, etc) actors in the leading roles.
Sure, it was filmed in New Zealand and directed by someone from there, but without the British and the Americans there wouldn't even be a Rings movie.
PPS: It felt good to rant like this
PPPS: Star Wars (the old trilogy) is still the best. (and has -along with Star Trek- the most loyal fans in the (movie)world)