Every author hopes they came up with something unique enough to draw readers.
While not everyone likes, or wants, to read about zombies, zombie books are still hot - and getting hotter. With the release of World War Z, zombies are big in the general public, too.
The fun, yes, fun, of the theme (or sub-genre since many writers consider it a genre unto itself) is that you can use zombies for whatever metaphor you want or to address whatever situation you prefer. In my book, GIRL Z: My Life as a Teenage Zombie (coming in August), zombies and turning part-zombie can include views on appearance, (a big thing to a teen), fitting in, and other issues. (Pre-order Girl Z: My Life as a Teenage Zombie
Writing about zombies also offers writers the chance to turn history on its ear as author Catt Dahman does with the Titanic. See what she has to say about her take on the Titanic - and yes, zombies - at GirlZombieAuthors.