According to Mike Mignola's very own ending note to this book, it was a throwaway idea that his editor Scott Allie and brilliant artist Pat McEown simply wouldn't let go.
And a fine idea it was!
In 3 short issue, McEown and Mignola pen a tale of the end of the world brought about by a revived ancient necromancer, Azzul Gotha, who unleashes a plague of zombies all over the world, to please his blasphemous outer dimensional crazy gods (HPL, anyone... ? ;-)!
You can see Mignola's quick wit in the dialogues and plot, but you'll have to credit McEown for everything else: The characterisation, the design of the fictional world (past, present and... otherworldly!) the beautiful ligne claire art, and evn the entertaining bonus section. Thanks to the flawless artwork and design, the art doesn't suffer a bit from being reduced in size from its original publication, quite the contrary!
This spawned a bevvy of very nice Zombieworld tales by different artists/writers, also collected in an equally re-sized volume. If you're a horror fan and you can get your hands on both books, you surely won't regret it!