Even speaking as someone who does not remember the book that well, this movie was not an enjoyable experience.
There is very little focus on the lovable Stellaluna adapting to life as a bird, and more focus on her antagonistic adopted siblings. Flap in particular is especially unlikable, while Pip is at least tolerable. Three completely unnecessary characters were added as well: Askari the spider is difficult to like thanks to his inflated sense of self, and a voice that reminds me of Snips from "My Little Pony: Friendship is Magic", but not in a good way. Horatio and Kazuku, a pair of fashion obsessed birds don't take up as much screen time as Askari, but were equally pointless.
The only really good things I can say about this were Stellaluna herself, plus her song "My Whole World's Turned Upside Down." which can be found on Youtube.
Stick with the book.
