Gimli was great too, I know people seem to think many characters were not developed enough, but by the actions you can learn a lot.
The actors were great, they were a lot into their characters, and for the first time, I saw elves as they were, quick, agile, terrifyingly effective in battle - just look at how Legolas dealed with the hordes of enemies without a single hint of fear in his eyes - these are elves as they should be.
And beside, as Arwen is to become a Queen later on, it was pretty good to see her have a great first appearance. I did not enjoy it because it was supposedly politically-correct to do so, or that I find Liv Tyler to be absolutely attractive it was just because I felt like even though it was a big change from the book, it was a very good one indeed, it makes you discover the power, determination, and courage of elves and the fact that even elven women, although great in their beauty and seemingly fragile in appearance do not have anything to envy to their male counterparts. As for the changes, well, I found good reasons behind all of them, and let me tell you right away, I was happy that Arwen saved Frodo, yes, maybe coming from a fan it will look like absolute heresy, but I enjoyed the scene a lot.