The film initially shows the downfall of a famed metropolis, then jumps forward many centuries to introduce "Milo," a somewhat awkward young man whose grandfather was captivated by the enigma of the vanished landmass. A very wealthy individual, "Preston Whitmore," enlists him for a risky journey to uncover the reality—and they set off with a submarine and a team that clearly has ulterior motives. The initial forty minutes of this lengthy story feels like something straight out of Jules Verne, largely consumed by drawn-out introductions of characters, some clumsy attempts at comedy, and by the time the plot begins to progress, I was already feeling bored. Michael J. Fox brings some personality to his role as the young man, and James Garner is clearly playing a sly character as "Rourke," but their performances aren’t enough to generate any real momentum in this technically proficient, yet unremarkable, animated movie. The visuals are bright, but it's obvious that everything is computer-generated; the animation feels flat and lacks detail. Combined with a fairly standard plot, this puts the film in a sort of Disney no-man's land. It’s not as poor quality as some released a decade prior, but it still seems like mass-produced work lacking creativity or the distinctive qualities that used to define this studio. It's acceptable enough for viewing, but ultimately unremarkable.

Source on TMDB