ISTG, I'd read the phone book if Ursula wrote it.
I've mentioned this before, but some writers seem to have a direct line to my heart and they can just reach in and grab my heartstrings and yoink!
Ursula is one of them. Everyone else has already said the good stuff about how she wrote a middle grade portal fantasy for adults that takes the best of both genres and combines them. More than that, I find Ursula has a gift for stepping back from both the glorious emotional triumphs that authors like CS Lewis use and equally devastating emotional tragedies that often drive more adult materials. Instead, she finds meaning in the small things and takes the middle road and the ordinary and celebrates it into its own kind of extraordinary. And I love her for it.