I would have preferred that Jackson keep to the book world, and modify only as needed to translate to the media. Additional information wasn't appreciated.
For example, wanting to show that the WK is very powerful by breaking Gandalf's staff - okay, as painful as it is for me to watch.
Aragorn falling off of the cliff into the river in TTT - what?
Eomer's not at Helm's Deep - okay, whatever; it keeps the focus on Aragorn, Theoden et al and shortens the list of main characters (i.e. no Erkenbrand).
Arwen at the Fords - okay, again to shorten the list and also keeps the 'romance' in the movies to attract a bigger audience.
Arwen at the Fords - "She elf..." need I say more?