I had a fantastic time reading this book. I love it when books use preexisting real-world beliefs to aid in their world-building.  It is quite heaven and hell based, but the reader still gets to explore other afterlife realms like Valhalla, and I LOVE that. I call it a mythology patchwork quilt when books pull inspirations from many mythologies/religions/fairy tales and this book is very that. 
The characters are so unique, quite a skrungly and unexpected handful of co-conspirators. Love some casual queer rep. The descriptions of everything from characters to settings in this book are unique and match the whole heaven/hell thing's tone well. There is an ethereal and otherworldly quality to the descriptions of lots of the characters, which fits so perfectly with the fact that they are all otherworldly creatures to a degree. 
Love me some casual queer representation.