A fantastic watch
Don't sit down expecting to see a typical film when you watch Fantastic Planet. It won't be like any movie you've seen in recent memory and it is definitely not a wide-appealing blockbuster, but it may still be for you.
This movie has a very cohesive and well-thought out story. Once it starts, it keeps moving. The story they crafted is well told and to me, the pacing is excellent to keep you feeling that the plot is always moving forward and always progressing, which is refreshing in a current age where it seems all movies must reach the two hour mark. At no point did it ever feel that there was a lull period or we weren't working in some way toward building the story.
I would not call it an 'art-house film' in some stereotyped sense - don't think it will have imagery or dialogue that leaves you confused at the meaning or left on your own to draw some vague conclusion meant for discussion on themes or anything of the sort. The story itself is neatly 'segmented' in a sense similar to chapters of a book which makes it easy to digest. I believe there is no need to read into this movie too much. The basic plot is given at the very beginning and the rest, to me, is simply an enjoyable tale to watch unfold. There are clearly elements with a deeper meaning that could be drawn from scenes in the film and the plot itself, but I don't believe you have to make that draw or deeper introspection to enjoy the film, unless you want.
I think one really standout aspect to this movie is the sound design - and design is clearly what occurred here. I imagine the audio team being shown the film for the first time and told "make music and sounds of this alien world." The 'music' is very unique and a character all its own. I think 'soundscape' may be more appropriate. It feels reminiscent of when sound engineers are told to create sound effects for an animated movie and they have to imagine what audiences think a crash landing could sound like and find creative ways to make that happen with all sorts of weird objects lying about the room. That's my impression for the sound of this film, except imagine they have to create this for an entire alien universe. What does THAT sound like?
If you're used to watching typical blockbuster films I would say you should still give this a chance for something a little different outside the norm. I think once it starts rolling, everyone is immediately thinking "what am I watching?" but stick with it, and not long after, you're along for the ride. You'll find yourself following the characters and the plot along as they suck you in on their journey and story.