There are three main things to consider when evaluating a children’s book. First, is it teaching your child the right kind of lesson. Second, how is the art? Third, will you get sick of this book after reading it ten times per day for weeks or months? Bestseller Mother Bruce meets all three criteria for a great children’s book. That’s probably why it’s an NYT bestseller and has a five-star rating on Amazon. 
As the title and cover give away, Bruce the bear is not happy about being a mom. He’s a guy who just wants to eat eggs and be left to his own devices. Unfortunately, due to a cooking accident, Bruce ends up with several little goslings who consider him to be their mom. This bums Bruce out, but he tries to make the best of the situation and [MINOR SPOILER ALERT] grumpily raises the goslings so that they’re well-adjusted geese.
Higgins is an animal lover himself, and it shows in the book. There’s none of that depressing Charlotte’s Web crap in this book. Bruce is a curmudgeon, and is frustrated with the goslings, but he knows they need love and attention and he gives it to them, raising them the way they should go. He’s never fake, and he also does what’s right.
I think Higgins’ message is that love is worth it, whether you are a grumpy bear who cares for others, or a happy gosling drawing out the best in others. You do get to pick your family to a certain extent, and you take care of each other.