You can tell the budget wasn't quite up to what they had in the previous two films. There's no massive battles full of nearly-realistic CGI monsters and animals. Still, the look and feel is still there. I didn't miss Eddie Izzard's voice in Reepicheep's mouth as much as I thought I would (and full props go to Simon Pegg for an excellent performance). And there's a lot to like.
For most kids, Dawn Treader is the favorite book. It's got adventure, strange places, pirates, and a cool sailing ship. It also has the most amusing writing. The first lines of the book are,
There was a boy called Eustace Clarence Scrubb, and he almost deserved it.
Of course, Eustace is the pivotal character, and his relationship with Reepicheep is as heartwarming and fun in the movie as it is in the book. The actor who plays him might not be as good as the original four children actors, especially Miss Henley, who plays Lucy, but the role is a difficult one, and his scenes with Reepicheep (which must have been especially difficult) are perfect.
The movie does suffer a bit from being short. Caspian's personal arc isn't given the attention it deserves, and Edmond's is barely given enough time to fully develop. Still, the bittersweet conclusion satisfies, and if this turns out to be the last movie made in the series, it'll be a satisfying conclusion.
And if it's not, it's set the stage very well for "The Silver Chair."