I cannot, in good conscience, recommend this book to anyone. The fact that it was self-published and endorsed by "Snooki" should have been enough to prevent me from buying it: Shame on me!
Cons: Exit Zero has an overwhelming number of spelling mistakes and grammatical errors which are both unprofessional and distracting. Example: The author uses the word "succession" several times throughout the novel; yet it's clear, from context, that he meant to use the word "secession"... I guess MS word didn't catch that for him.
Deficiencies in editing aside, the book also lacks in terms of its characters. At best, the characters of this book are clichés or stereotypes (an Italian-American crime boss); at worst, they are completely flat and uninteresting (like either of the two 'guns for hire').
The plot makes little sense and it appears to have been dreamt up, and written, in a single afternoon. I had more detailed plots in the pages of my childhood sketch books than the author had in over 300 pages of text.
Pros: The ONLY pro that I can point to, amidst the wreckage of this tragedy, are the short zombie "vignettes" between main chapters. Some of them show tiny slices of the apocalypse from the perspective of normal people, which lends fleeting humor and relatability to those characters (or victims, as the subjects of the vignettes tend to die).
Although Exit Zero has what could have been an interesting premise in it's apocalyptic vignettes, the execution of every other aspect of the book is so poor that this one positive feature cannot redeem the novel, nor can I recommend it to ANYONE. There are better zombie stories out there and they're not too difficult to find.