Well, I had been meaning to watch this for a while (thank goodness I found it for cheap).
Based on the Nickelodeon series of the same name ("The Wild Thornberrys", of course), the story tells of a family that travels around the wild parts of the world, filming their father's wildlife television show. The family is typically dysfunctional: the "normal" father and mother, the oldest daughter Debbie (who annoys me at points), the wild child Donnie (he's a strange boy, he is. Also is annoying.), and of course the star of the show, the nerdy yet adventurous Eliza (who looks like a fusion of Steve Urkel and Pippi Longstocking) who was given the power to communicate with animals (as long as she doesn't reveal her secret to anyone, of course).
I've only seen a bit of the television series, but I knew enough of the basics to understand the movie (especially since they did do a quick summary of the plot of the TV series within the couple of minutes before the title screen). This was an enjoyable piece to watch. The character design and feel of the whole thing stayed true to the series (which is a good thing), the music was beautiful (especially the Paul Simon song, "Father and Daughter", which took me a while to get why it was used in the movie . . . but it was still the best out of all of the songs used), and the flow was . . . quick and easy-to-follow (a good thing for little children to watch). Some parts of the film could have easily been cut out, but I feel glad that they didn't.
In conclusion, this is the way a TV-based feature film should be: true to the series, through and through. This is a charming family film that should not be missed!
(Additional thought: While watching the film, I remembered that Lacey Chabert provided the voice of the lead character, Eliza. Her character sounded quite familiar to another character that she had voiced: Balto's wolf-like daughter, Aleu in Balto: Wolf Quest. The two characters are quite alike, and I felt like I was hearing Aleu instead of Eliza during some scenes! ha.)
Four stars from me!