The second of the seven movie adaptations sees the Pevensie siblings (Peter, Susan, Edmund, and Lucy) one year older than when they returned from Narnia at the end of The Lion, The Witch, And The Wardrobe. However, Narnia aged an astonishing 1,300 years in that time, and was long ago invaded and conquered by Telmarines. Most of the Telmarines hated and feared the living forests and the creatures within, oppressing, attacking, and killing them until the trees slept and the few surviving creatures disappeared into the land’s deepest reaches. Eventually, they became only whispered legends and stories among the Telmarine people. Now, the only notable Telmarines who could be considered ‘friends’ of the supposedly-extinct Narnians are (the partially-believing) Prince Caspian the 10th and his secretly-half-dwarf tutor. Caspian’s evil uncle Miraz had murdered the Prince’s father, Caspian the 9th (covering up the death as a natural one), and only left Caspian 10 alive because he had no eligible heir of his own; but when Miraz’ son is born he has no more need of his nephew and the Prince must immediately escape. Fleeing into the forest, Caspian’s new life begins… and, one day soon, he is destined to help free the Narnians and then become their rightful King.
General Changes: The most significant (and probably most irritating) general change is to Peter’s personality, which at times is now somewhat less than noble. Trumpkin’s personality, on the other hand, is changed for the better; he’s much more serious and wittily sarcastic (then of course gradually softening up to, and becoming rather fond and protective of, Lucy). Prince Caspian’s tutor is cleverly called “the Professor”. Caspian is older… and, due to this, there is some mutual attraction between Susan and Caspian. The forest gathering is more hostile to Caspian at first. The summoning of the White Witch is longer, creepier, and excellently intense. For pacing reasons, some scenes are shorter (for example, Miraz’ men follow Caspian immediately as he escapes; the Pevensies figure out that they’re in the ruins of Cair Paravel a whole lot quicker; only Edmund challenges Trumpkin; the scene with Lucy and the bear only goes as far as Trumpkin cutting into it; etc.). There are some minor changes of detail (Caspian is not totally knocked out by his run-in with the tree branch— Nikabrik finishes that; the treasure room door is hidden by vines and a sliding stone panel; the “door in the air” is made by a living tree; etc.). And several events are moved around in the timeline (Caspian blows Susan’s horn and Trumpkin is captured near the beginning of the movie rather than near the end battle; Miraz is crowned during the movie instead of years before; etc.).
Deletions: Caspian and his tutor do not stargaze before the escape. Caspian’s long introductory tour of the forest and visit to the Faun dance is instead completely replaced by a short new scene that introduces one character earlier and brings Caspian straight to the gathering. The most significant (and probably most-missed) deletion occurs because Lucy’s meeting with Aslan now takes place in two parts— the first part in a vision/dream, the second part during the end battle; because of the split, the sequence where she must go back, wake everyone, and either have them follow or go with Aslan by herself/the journey that they all consequently take with the gradual revealing of Aslan to each individual/the conversation after is gone (however, one or two small parts of it, such as Trumpkin finally believing, are mixed in with Aslan’s words to Caspian after the battle victory; and from Peter’s much more humble attitude at the end, you can assume that portions of the conversation took place offscreen). They are not shot at when they reach the work at Beruna; they just realize there’s no possible way through. The Bacchus/Silenus/etc. drinking party (which may have been better left out anyway! 
) and the run through the town(s) freeing schoolchildren/Caspian’s old nurse/misc. others were also cut; because of this, Susan fights in the end battle. The triumph feast is not shown onscreen, though a celebration is implied. And there are some minor deletions of explanatory dialogue.
Additions: A boy from the school across the road from the Pevensies’ tries to talk with Susan before and after their adventures in Narnia. There is a fight between several boys (including Peter) in the train station. Caspian’s many losing raids on Miraz’ army are replaced by a long and intense castle-infiltration sequence. There’s one surprise little extra to Susan and Caspian’s farewell. And a few other small additions fill in backstory, character-build, and accommodate moved scenes.
This actually turned out to be one of the most unusual reviews we’ve undertaken, as the movie’s quality is so disparate between its elements (adaptation vs. presentation) that we were even forced to split its rating.
As an adaptation— well, let’s be honest; there’s a fair amount that pretty much fails. While a few of the numerous deletions, additions, and changes (such as removing Bacchus’ drinking party and making the White Witch summoning even more intense, etc.) were certainly for the better, and even the castle-raid sequence could have been forgiven (as it was added to replace the many losing raids of the book), the amount and weight of many of the other changes— from Caspian and Susan’s mutual crush (which was intended to make the story a bit more realistic, but could have been done a bit more subtly), to the somewhat drastic change of Peter’s personality, to excising Caspian’s tour of the forest and basically the entire end (Aslan freeing and healing the townspeople, which could still have been done even without the Bacchus stuff; the feasts; etc.), to (most significant of all) the deletion of nearly the entire night sequence with Lucy and Aslan (and a great deal of change to what was left)— rightfully annoyed and even offended a lot of fans.
…And yet, if you simply watch it as a movie alone, it’s excellent. Cinematically it has somehow improved, and features even better and more realistic special effects. (They also combined that with a grittier presentation, which we appreciated quite a bit.) And, of course, the acting is also even better overall. Then there’s the new and fully updated dialogue, which is genius (and quite often hilarious— the witty humor throughout the movie, both in actions and in dialogue, is wonderful ). Plus, the parts that aren’t humorous are much darker and often downright intense, adding further to the realism (and the appeal for teen and adult viewers).
In the end, the best way to put it is that Prince Caspian as a movie is great enough that we would certainly recommend seeing it, but without expectations of a close hold to the book.
Our ratings for The Chronicles Of Narnia: Prince Caspian:
Adaptation, 2 & 1/2 Stars. 
Presentation, 5 & 1/2 Stars. 