I am a huge LOTR fan. I have read the books many, many times over, and have even attempted to read the Similarion (sp?) on a number of occasions. That said, I think that these movies are great!!! Yes, I know, they screw with the story somewhat (change the order of events, make minor characters more important, leave out other characters, and add a bit from the Lost Tales), but overall I think that Peter Jackson has done a great job! Inevitably, when a movie is made of a book (especailly such a great one) things get cut out and rearranged, sometimes to the point where the movie does not resemble the book in any way. Though Jackson has made changes to the books, I think that he has kept to the general spirit of the books and has done them justice. Remember, as big a budget as this was, he has to appeal to a very wide audience, not just us LOTR geeks, and these movies are coming out 1 year apart, so for the sake of continuity some things needed to be changed. Let's face it, these books are not easy reads, especially the first time through. Storylines get twisted and obscured and can be a little confusing, not to mention the vast number of characters. I think that lots of what Jackson did was done for simplifing the storylines.
As for The Two Towers, I thought it was great, possibly even better than the first movie.