Mickey Finds a Kitten tells of when Mickey found a kitten, and how Pluto felt abandoned, since Mickey was paying so much more attention to the kitten than to him.
Pluto doesn't understand why the kitten is praised for doing things that Pluto isn't allowed to do. He decides he'll try to act like the kitten, but he is just scolded for doing so. Finally, Mickey realises what is going on, and tells Pluto that he shouldn't act like a kitten, because he is the world's best dog. So Pluto decides he'll always be Pluto, the dog, and he won't try to act like something he's not.
This one is a story about being yourself, though it's got a little similarity to 'new baby' stories like Thumper's Little Sisters. It's not bad, though of course it's got only a very simple story. I think I would prefer this one to Thumper's Little Sisters even as a 'new baby' story--this aspect might be a little subtle for very young children, but that's what parents are for, isn't it?
This one is kind of similar to the old Disney short "[Mickey's Pal Pluto]" from 1933--in that one, Mickey finds several kittens, and they cause Pluto trouble, and he's treated poorly and ignored by Mickey.
The illustrations are pretty good. You can certainly feel poor Pluto's confusion. A lot of the backgrounds are very simple, though--often just the wall meeting the floor, or just a gradient meant to represent this.
Mickey Finds a Kitten is a fine book for young children, though it has little to offer older readers.