I actually have been fairly disappointed in this series up until this issue. Pablo Raimondi and Mark Farmer (pencil/inks) have done a consistently excellent job on the artwork (And Paolo Rivera's covers are clever). My problem actually has been Ed Brubaker's story, or rather, a situation of Formatitis if I ever saw one, as "Doom's origin" really, really, reeeeeally doesn't need six issues to tell.
However, while the format affected the middle parts of the story, the effect is less upon the conclusion of the tale, which is, well, this issue.
This issue is about Doom becoming the actual king of Latveria, and Brubaker handles it extremely well, especially the way that Doom is SOO dominant that even his enemies want to join up with him (which is expressed in one super cool scene that Brubaker even has the decency to specifically set up, when a lesser writer would have just had the cool scene happen withOUT the set-up, and I would have let the writer slide on it, as the scene would be cool enough on its own - but cool AND set-up well? That's awesome).
Meanwhile, the king of Latveria is an interesting sort, and there is a nice touch regarding the king's costume. The final showdown between Doom and the king is handled quite well.
Later, the exploration of Doom's history with Mephisto is done well.
Finally, when we cut to the present, there's a nice Twilight Zone-esque ending that reveals why we've learned so much about Doom, and also we even get to see Doom's face (maybe)!!!!
So, while I would not recommend the series as a whole, I would recommend Books of Doom #6. Good stuff.