The kids seemed to enjoy 365 Penguins. They laughed at the funny parts, especially at the ending, and enjoyed watching the family try to solve their penguin dilemma. In addition to being a cute story with a sense of humor, it's also a math story full of equations employed in the family's attempt to organize their growing pengin collection.
Math is not really my favorite or my best subject, but my niece loves math, so I thought she would enjoy that aspect of the story as well. I think that she actually found it somewhat interruptive, though, and wasn't interested in being pulled out of the story to solve a math problem. In the end I just read the story and let her appreciate it as a story. I did like the author's attempt to show kids real-world applications for math, since a common refrain is "when am I ever going to use this?!"
I was a little concerned that the kids would not be very impressed with the pictures in this book. Black, white (of course), orange, and blue made up the palette used, so there were no in-your-face, eye-poppingly bright colors. But the kids didn't mind the pictures at all, and even seemed to enjoy them.
In the end, this is a cute, funny book that the kids enjoyed, and that teachers and parents could use as a math tool.