So the movie itself wouldn't be considered bad but kind of cute and I understand it's mostly for childern (I also enjoy the atmosphere and the style that's why I kept going). The main issue I have with this is how they changed the story. I know adaptations don't always need to stick to the original 1:1. It's just that they completely missed the entire purpose of the story. During her journey Thumbelina is forced by anyone to marry someone and always barely escapes. While the prince is the only one who asks her if she wants to marry him and truly considers her feelings. (Which the animated "Thumbelina" version from 1994 captured perfectly. That's why I might feel that version is superior). While in this anime version... well... They also kind of took the whole point of the prince changing her name out of context. Meeting someone for the first time, asking them for their name and then being like: "Nah. Let's change your name." Just NO.
This whole issue is also why the characters are boring, one-dimensional and quite the opposite of what they are supposed to be.
I know you could think that I'm taking this much too serious for such a light-hearted movie but maybe I do (because Hans Christian Andersen is one of my favoirte writers of all time so I'm very critical over his story adaptations).There's actually one animated version of "Thumbelina" which is so lovely (mentioned above). And I know for a fact that animes from this era can do much, much better than this one (story-wise).
Overall not completely a waste of time but there are too many flaws to fully enjoy it.