My first grip with this product was that it is laid out in two pages per sheet. Which I find very inconvenient. On the layout front I would add to this the illegible font used for the three major headings and the random approach to page numbering. In this book page numbers seem to crop up at random intervals. Probably more then half the pages don't have one.
Also this is not a settings book. There is no more then the skeleton of a setting here. What there is instead is a poorly organized set of new custom moves for Dungeon World. Note there is no index of moves or any other attempt to make this a useful reference of new moves.
Also absent are any substantial examples of the new moves being applied in play. And really there is so much in terms of new rules here that an example was warranted.
You do get a map with some interesting locations drawn in, but these go mostly unmentioned in the text, and certainly don't get any kind of writeup. Heck even the one Key NPC in the whole book is not adequately described. We get names and powers but no real back story or personality.
All in all Dark Heart of the Dreamer does not compare well to other supplements for Dungeon World. Especially considering that some of the others are distributed free and this one costs 1/2 as much as the core rules of the system.