Both assessments are somewhat hyperbolic and off the mark. I should probably preface my review by confessing that I’m not a big fan of director Andrew Stanton. Finding Nemo (2003), in my estimation, is bloated and overrated; Wall-E (2008) takes unfortunate leave of its ambitions after the indeed noteworthy first act and also exhibits pacing problems.
John Carter isn’t exactly perfect, either, with many of the same issues. Despite the planet’s name having been pruned from the title, “the good stuff” is on Mars, and the film takes too long to get there. The Edgar Rice Burroughs subplot set on Earth decades after the main events of the film, for instance, is mostly superfluous and would be so entirely if not for an out-of-left-field twist ending. The introduction of John Carter himself, too, drags quite a bit. His backstory could have been dealt with more efficiently on Mars than on Earth, I feel, and indeed what we get of it on the Red Planet works better than Carter just randomly being a dick to the United States military.
Throughout the movie, there are also some silly bits of physical comedy which seem weirdly-tacked on and not in keeping with the tone the rest of the movie seems to be trying to establish for itself, which is the sort of earnest excitement at looming adventure I like (and miss) in this sort of film.
From a modern perspective, many elements of the story are weird, laughable, even: It starts with the fact that the whole genre of planety romance has been superseded by our current scientific knowledge and doesn’t end with the silly names the warring Martian city-states get, like “Helium” and “Zodanga”. But based as it is on a 100-year-old novel, it’s not a modern story, and it’s to their credit that Stanton and his screenwriters treat their material just the right amount of seriously.
CGI notwithstanding, John Carter is an old-fashioned throwback to the adventure tales of yore, and I’ve said before how appealing that is to me when done well, as it (mostly) is here. I wouldn’t say that the film is an instant classic. Aside from what I’ve already mentioned, there’s also a lot of exposition in the movie that feels like both building up the world for sequels and holding the hands of clueless audiences instead of sticking only to what is needed for the first film. But when it works, it works as a thrilling adventure with several memorable characters, both heroes and villains, a rousing musical score, and a serviceable plot. John Carter‘s floppy reputation is undeserved, and it’s actually my favourite Stanton film at this time.