I've never read any zombie novels before, but that's mostly because I've never even been into zombie movies. I'd watch them now and then, but the characters in most of them were so stupid that I couldn't stand it. "Oh hurr duurrrrr, what's behind this door in this dark room?" It made me shake my head in embarrassment.
But Monster Island surprised me. The characters were pretty smart for the most part. There were times when the girl soldiers were acting like the zombies could plan and be organized, but the author addressed this as a flaw so I could kinda buy it. I think my favorite character was Gary, at first anyway. The idea of a thinking zombie is cool and something I rarely see, and the author's take on it was fresh. The way his zombie-ness was described (hunger, just death in general) was very well done and made me sympathize with him.
It was when Gary got his weird psychic powers that I started to go, "What?" I guess it shouldn't have bugged me as much as it did, but t seemed like a bit much to give zombies psychic powers. I know that it was explained pretty well so it didn't come completely out of nowhere, but zombies are zombies to me. Sentient ones are ok, but that's about all that my brain can accept.
I liked the colony of humans that had to live in the tunnels. It seemed like something that would really happen. People would try to scrape up what was left of society and make the most of what they had.