Poesy the Monster Slayer was not my cup of tea. Poesy seems to be a bratty child. I understand her need to “fight the monsters” due to her fears 
(though she says she is not afraid, but her father who is actually afraid) but why did she have to be nasty about it? A quiet “fight” would be fine and a great lesson to children. Maybe say Monsters hate whispering so she whispers to them. Or point to a nightlight because they dislike light (her which takes the form of Poesy’s wand). I am all for girls standing up for themselves, but did she have to “stab/strangle” the werewolf with her crown? Or throw her midnight snack (drink and an open banana) at the vampire? What really lost this for me was when Posey takes Frankenstein’s head (who sadly sits there and lets her) and puts it on one of her stuffed animals. Regardless if this is “real” or her imagination, it was disturbing at best. And “Sid from Toy Story” came to mind.
If Poesy had “nicely” fought the monsters her fears would have been taken care of. This would not have added the parents walking up tell her (by using not just her first name and not one but eventually all her middle names, followed by her last name) to go back to sleep. And yes, it was funny that the father used swear words when he stepped on a toy, but it was totally unnecessary. Parents will recognize the “turning into zombies” aspect of having a willful child who will not sleep/does not allow your sleeping. Parents will recognize their child. I personally am old school and do not think this story cute or clever. And while I am not always a fan of the “parent less” child or the “clueless” parent (i.e. unaware of their child’s nighttime activities) I think allowing Posey to solve this one by herself could have worked better. Of course, the point is this is a fresh take on things with having the parents trying to make the child behave and go to sleep and not coddle them with getting drinks, hugs, stories, etc. throughout the night.
While it is never easy to create a book (a lot of time, effort and love that goes into it) and I appreciate the hard work behind this, I am sorry to say that this book is not on my recommended lists. I have not read Cory Doctorow, but this picture book makes me question if I want to read other things. I will, however, try to read a novel and a graphic novel by them to compare the genres.
The only saving grace is Matt Rockefeller’s illustrations. The contemporary look to them is the perfect choice for the modern story. The illustrations are boldly colored and perfectly detailed. You see the fact Posey comes from a diverse family background and while the art is “cartoonish” it is realistic, and the people look like your family, friends and neighbors. The mother wears a tank top, the dad his boxers. The realism of their tiredness showing on the faces is a nice touch. Yet, it was unable to save me.
Of course, all the things I dislike about this book might be the things that allows this book to be a favorite for you and/or your child. Please let me know in July what you think.