The Two Towers is a very enjoyable film. I suspect its greatest fans will be those who have not read and loved the book. Picking holes and making comparisons is almost irresistible if you know the book well and the thoughts, decisions and actions of Tolkien's characters are loaded with meaning for you. Peter Jackson has probably made /almost/ the best job possible given the limitations of time. Personally, I would have been very happy if he had made it into 6 films each lasting 3 hours (or more) and followed Tolkien's story to the letter. But that would have been a huge and expensive project, most unlikely to find funding. What he has accomplished is still impressive. As far as possible he has tried to convey the story and meaning as the author intended. It seems clear to me and many other lovers of the book, that he hasn't entirely succeeded.
This is the second part of the Lord of the Rings trilogy and continues the tale after "The Breaking of the Fellowship" chapter of the first book. It is necessarily more fragmented than the first film and follows the book less faithfully than the first film. The fellowship is now split into 3 groups: Frodo and Sam, on their way to Mordor to destroy the ring, Merry and Pippin being carried towards Isengard by orcs, Aragorn, Legolas and Gimli in pursuit of the hobbitnappers. Some of the departures from the book do seem unnecessary and change some of the subtle meaning the author (I believe) intended to convey. The most heinous of these liberties, change the personalities of the characters and the less bad just cause slight patches of nonsense in the story.
By some rather annoying jiggery-pokery, Arwen keeps popping onto the screen, mainly in dream sequences and also a scene in Rivendell where her father, Elrond, persuades her to leave Middle Earth and leave Aragorn. This is a fairly major departure from the original story and seems no more than a ploy to distort and over-inflate the romantic angle. It changes the personalities of 3 important characters and actually wastes rather than saves film time. Gollum, although a wonderfully well made character in the film, has been turned into something like a cute but naughty dog with a split personality. He seemed very much more sinister and dangerous in the book. Faramir has been changed from noble, strong-minded and wise to something more weak-minded and indecisive.
Where possible, Mr Jackson has used Tolkien's words although the speaker of the words may be different. For example, Treebeard says some of Tom Bombadil's lines. This is quite clever and difficult to spot. However, there are places where Tolkien's words are used, but because of alterations to the story, they don't make sense. There is an inserted scene in the film where Treebeard presents Merry and Pippin to Gandalf in Fangorn forest. Later Treebeard is telling the hobbits that he's going to keep them safe, as Gandalf instructed. So when Gandalf later meets Aragorn, Legolas and Gimli in the forest, you would expect him to have remembered that his name is Gandalf, but he has to dredge it up from the depths of his memory when they address him by that name, which makes him look senile. Tolkien's Gandalf was certainly not senile. Legolas is treated as though he were a youth. Gimli calls him "laddie". Tolkien's Legolas is actually many hundreds of years old. Fangorn (Treebeard) is the oldest creature walking Middle Earth, and Fangorn forest is so old that it almost makes Legolas feel young again.
Despite all the criticisms (and there are many more), it's still a great movie, especially if you come to it fresh - having watched The Fellowship of the Ring but never having read the Lord of the Rings. If you've read the book and particularly if you've read the book many times, you can best enjoy the film by taking a laid-back attitude to its relationship to the book. Accept that a lot of the subtle meaning is lost but it's still a gripping yarn. I thought the actors were all excellent and didn't mind at all that Legolas skate-boarded down the steps at Helm's Deep or that Gimli was a comedian. The orcs were very well done - a really revolting lot - the dark lord's GM elves. The ents were as I imagined them. I was pleased that the wargs didn't look anything like wolves (a departure from the book I fully approved of). The music was very good. I rate this film a five star because nothing's perfect and I would have thought this came very close if I hadn't been spoilt by reading the story it was based upon.