This was a favorite of mine when I was four. I had a little sister, and possibly the battle to feed the baby in real life added to the charm of this.Additionally, infants are not always fun. Only children may not get it. The reader is to feel empathy for the main character, the dog, not the baby.
As they have with Where the Wild Things Are, modern parents seem to over-think this a little bit too much. It is only scary if adults think it is scary; the main character's food obsession adds plenty of comic relief. We know that the baby is not in much danger... her vile disposition almost assures us that if the lion eats her, her will just spit her back out. We can also wonder if Jenny will eat Baby instead, saving the Lion the trouble.
Your child's vocabulary is as big as you make it; I love the sentence structure and comic timing in this book, with repeated phrasing and subtle asides. Maybe I did not "get" it all at age four, but it delighted me.
The artwork is divine, no bright mishmash of primary shapes and colors here. Where the Wild Things Are is similar...*plex illustrations that convey a lot of information without knocking your eyes out. Jan Brett is a modern illustrator who takes detail and beauty above what is popular, and I feel parents should give their kids the ability to enjoy different styles, as long as the story and writing support that...which this does.
This book is also a nice gift for adults who have been through rough patches. Inspiring message of following dreams, having integrity and courage, and taking risk rather than settling for what is comfortable.