Erin and I saw The Two Towers today, taking Teri, who hadn't seen it yet.
I would have to say that I enjoyed the movie even better the second time. I think this was because I now knew which parts they would change and was ready for them. So forewarned, I was able to enjoy the whole movie on its Tolkien merits. Good sign.
We met my parents for dinner. They'd seen the movie a couple of days beforehand and my mother, the Tolkien purist, was still fuming (figuratively) over the changes they made to the story, especially Faramir (she's not the only one; the best review that I've seen describing all of the changes is right here). She was also wondering why Eomer replaces Erkenbrand leading the Rohan cavalry to save the day at Helm's Deep.
Actually, of all the changes to the story, this was the one I had the least problems with. In the book, Eomer is thrown in jail by Grima Wormtongue while Erkenbrand (whose name I had to look up just now) is off hunting Orc with his brand of loyal riders. Although this arrangement gives Aragorn and Eomer more time to work together (and thus build their strong friendship), the movie's arrangement streamlines the plot and the list of characters. Erkenbrand works in the books, but in a three hour movie, he would be superfluous, just like Glorfindel. I also believe that this gives Eomer a stronger character arc. He represents loyal Rohan on screen, and his arrival at Helm's Deep salves the wound between him and Theoden, his uncle, and represents the rebirth of Rohan as a proud nation.
Again, I point out that what works well on paper doesn't come off as well on screen. This isn't a complaint against Tolkien as much as it is a complaint against the film medium. Books are more subtle than films could ever be. Teri pointed out that the last book with as much backstory as the Lord of the Rings to appear on film was Gone With the Wind. In that case, the backstory was the American Civil War -- which most of the audience could be expected to know about. An informal survey suggests that as many as 40% of the audience for The Two Towers has not read Tolkien's work.