[Boromir88]

I agree with everything Sir Korhan says, well said. To add a few things...

Beside just introducing Arwen it sets up the whole love story background between the two. Which is important for the movies. Tolkien gives us a lot of the background in the Appendices (which Jackson ended up using a lot of it for his "love story") However, it's important to set up the background between the two early in the movie. Because for the most part in TTT and ROTK Aragorn is around Eowyn and Eowyn is trying to cozy up to him. Then when Arwen shows up at the end to marry Aragorn it may leave the audience going "who's this elf chick, why is she important, hasn't Aragorn been with this Rohan chick the whole time?" So, I think it's important to establish Arwen as an important character in the first movie, as it sets up the love story between the two, and people aren't caught so off guard at the end as to why Aragorn married Arwen.

I don't like the portrayal of XenaArwen in this scene, I think they should have left it as it was and have Elrond command the river and Gandalf add the white horse effect...but I am not bothered by the change of taking out Glorfindel and putting in Arwen who we will be seeing later on in the film, where Glorfindel more or less makes a one time appearance.