One of the most interesting aspects of Monster Island is how the story is told, and the different perspectives you are given within the story of different cultures' take on the pandemic, even including one of the undead. What this lends to the story is that then you see the events from many different perspectives; the cliche main character who is horrified over everything that is happening and is just trying to find his way to his daughter, the Somalian's view of the situation as a part of life and death as an honor, and the undead perspective of acting according to nature and trying to survive.
The fact that the story does alternate between the view of the living and the dead is an interesting twist few zombie novels have. Here, the story had an incredible opportunity to explore the depth of why the undead act as they do, and though the novel touches upon the reasons, it never explores the reasons why in any real depth. What the novel first touches upon in terms of the undead is two aspects; their actions are based partially upon their nature, and partially upon staving off death.
Another interesting aspect the story took on was that all of the zombies have a supernatural connection that allow them to move and act together. This is something that most stories never address; how zombies, without any eyes, noses, or ears, can possibly sense survivors. Also, taking a supernatural approach to the outbreak allows for some leeway in terms of science. If a story tries to give an entirely scientific explanation, then a lot of questions can arise as to how a pandemic can spread so quickly, how the zombies react, why they are resurrected, etc. Giving it a magical explanation allows for all those issues to either fall to the side, or to be explained pretty easily with "oh its magic", or to be given more novel explanations.
The idea of intelligent undead is another interesting twist that makes the story much more tense. Whereas normally the undead aren't much of a threat, acting as a motivating force for the main characters, they end up being a serious threat, and with how the entire story is told, the ending is totally open, because no favoritism was shown to any of the characters throughout the novel.