Considering the relative brevity of the novel "The Hobbit" compared to the gargantuan "Lord of the Rings" trilogy, the decision to split the book into three films of equal length as the prior trilogy was disconcerting to fans.

Was there enough content to fill that much screen time? Even at their best, the "Lord of the Rings" films had a tendency to drag. How, then, would a children's adventure story fare when stretched out to a total 9-hours?

If this first film, directed by Peter Jackson, is any indication, thankfully, the answer is surprisingly well.

"The Hobbit: An Unexpected Journey," is a brisk, lively adventure which succeeds largely due to its lighter tone and stronger lead. The film, much like the book, plays like a serialized adventure travelogue of Middle Earth.

One of the film's greatest strengths is Martin Freeman as Bilbo Baggins. Freeman brings a lively comic sensibility that makes him a more enjoyable protagonist than Frodo. The film walks a careful tonal balance between the lighthearted nature of the original work and the grave implications of the coming war.

Less successful than the tonal link between the films is the attempt to clumsily visually bridge the two trilogies. The opening scene takes place the same morning as the opening to "The Fellowship of the Ring," and features a noticeably older Ian Holm and Elijah Wood as Bilbo and Frodo. It is somehow both distractingly long and disappointingly shallow. Little content is introduced in this extended prologue that affects the story.

Even with the prologue, the film breezes by the Shire under the assumption that audiences are already familiar with it. As a prequel, "The Hobbit" should have taken the time to ease viewers into the fully-realized Middle Earth.

As soon as Freeman takes over as Bilbo though, the film takes off and doesn't stop moving until the very last frame. It's a rare beast, a successful prequel that uses the inevitability of the later films to its advantage rather than letting them weigh it down.