Interesting to read some of the critical responses cited on Wikipedia:
"Strange World is a Disney milestone in terms of representation – but as a storytelling experience, this dazzlingly animated adventure offers little audiences haven't already seen."
"it's the characters as much as the environment that make this vibrant, Journey to the Center of the Earth-style adventure movie colorful and diverse in all the best ways. Great as the people and places they explore may be, however, the relatively unimaginative story consigns this gorgeous toon to second-tier status ..."
Certainly there is a homage to some classic old SF films, but I think the response that it's good but not great is a fair one.