As a long time tolkien geek i have to say. The movie accompishes so much, but the writers let their pride lead them astray. Of all the things they added only the oliphant scene worked.
The orc landing craft,
Denathors 1km flaming run,
arwen dieing if the ring isnt destroyed,
arwen turning back from the grey havens because of a vision of her child,
aragorns doubt about wanting to be king,
doppy the big orc leader,
sneaking up to light the beacon,
the counter attack to take osgiliath back
Parts that they left as close as possible amazed me. I would have never thought you could film the captivity of Frodo so accuratly and easily. I couldnt imagine how they would make that whole section in mordor. But he pulled it off increadably well.
The battle of the pellenor fields was increadable. Why they changed the timeing so that there was no confrontation between the witch king and Gandalf and there for allowing the bad guys into the city is beyond me as well.
In the time they showed the stupid fires of gondor going to rohan and arwens biological clock ticking they could have included the scouring of the shire. The book with out the scouring of the shire is a different story.
Why it was neccessary to rewrite aragorn as a hesitent man who didnt want to be king is totally beyond me. Its like if the master and commander screen play had Jack Aubery be a hesitent man who didnt want to be captain..