This review covers both versions of "Flatland" released in 2007, one by Ladd Ehlinger, Jr. with a mostly unknown voice cast, and the other by Jeffrey Travis with some Hollywood big names providing the voices.
The source material for both is the 1884 novella by Edwin A. Abbott, but the approaches of the two films differ radically. The book is a staple of science fiction, and one of the few to address mathematical issues at its core. Being a product of its time, the book is technically naive, and politically incorrect based on current sensibilities.
The Travis film is visually slicker, but significantly shorter, and tackles philosophical issues relative to the passage of time from initial publication. As such, it tampers with the plot to mixed effect. Unlike some others, I have no problem with some of the revisions to the underlying plot since they do help bring some of the book's major issues into somewhat sharper focus. On the other hand, they also add a "feel good" and politically correct sensibility that seems out of place.
The Ehlinger film is much truer to its source material, which is both a strength and a weakness. Given a current perspective, its 19th century depiction of the political and social subjugation of women is a distraction that the Travis film avoids. It's also a longer film and could have been more effective with some of the same plot and editing license employed in the Travis film. Where it does tamper with the plot, some of the decisions are questionable as other reviewers have pointed out.
So which is better? In my opinion, the short answer is the Ehlinger film. Despite its length, political incorrectness, and technical inferiority (the animation of the Travis film is much more sophisticated), it resonates at a technical level to a degree that the Travis film can't match. As a scientist, this means a lot to me. On the other hand, the Travis film resonates on an emotional level that the Ehlinger film can't match. So the answer may be whether you're looking for technical insight or emotional satisfaction.
Most jarring in the Travis film is that, unlike the Ehlinger film, the animators never quite caught on to the implications of a two-dimensional universe. It is filled with objects which are instantly recognizable to us, yet would be clearly impossible or meaningless in the film's reality (e.g. the protagonist's daughter has toys which only make sense to someone with a 3-D perspective, and how does he open his briefcase?). The cover art is an obvious first impression example. The Travis film's characters look more human, but ask yourself how their eyes work. One detail of the book is that looking at a Flatlander from above, all of his internal organs are clearly visible, as they should be. Travis' animators hint at this, but don't meet it head-on. The Ehlinger film's animators may not have had the resources to make as slick a film as Travis', but they obviously gave a great deal of thought to what they were doing (or maybe not, since the necessary designs were all in the book). In short, Travis had the budget, but Ehlinger had the passion for the project - albeit perhaps a bit too much respect for the source to create a truly superior adaptation.
The differences reflect different target audiences, though. The Travis film is an educational short film which was obviously meant to be viewed by classrooms of middle school and high school students. As such, it had to be socially inoffensive while conveying concepts of geometry that would never occur to non-mathematicians. That it includes recognizable names voicing the characters will help it grab a bit more attention - an educational short film for the "X-Files" generation. The Ehlinger film would mostly appeal to people with a college level interest in mathematics, or others who are already familiar with the book.
Neither film is perfect, but I'm giving the Ehlinger film a rating of 8 and the Travis film a rating of 6. Depending on your sensibilities, your conclusion may be exactly opposite of mine, so I hope this review includes enough information to guide you to an informed selection.
Or, like me, you could simply buy both... ;-)
