I've been telling my friends that Dead Island seems like Borderlands meets Dead Rising to me. Nice to see the experts agree with me too.
That said I personally don't think the game is so bad it's unplayable. It's just pretty much like Frankenstein; you can clearly see how the parts of other games have been stitched together to make it. Frankly I think the combat mechanics do work with the right strategy. The problem I see is that if you don't adopt the one strategy that seems to work, you're going to be in serious trouble. Because of this, there's really no point for the survivors to have different expertise. You've got four types of combat: blunt weapons, blades, thrown weapons and firearms.
Now I'm only into Chap. 3 or 4 so far, so I can't speak too much to what you'll start seeing in later levels, but so far the winning strategy I've found is to throw every weapon I have at the zombies I can keep them at bay and not take a lot of damage, so long as I give them the occasional mighty boot to the pelvis. If they start getting too close, a fast kick will knock them down long enough for me to grab one of my tossed weapons and plant it in their forehead.
To me, this seems like the only sensible strategy because guns and bullets aren't readily available to the point of barely being an option and because strangely enough, swinging a weapon makes it take damage and wear out quickly, but throwing a weapon doesn't seem to hurt it at all. After using a sickle to hack down about a half-dozen undead by tossing it into their chest cavities, it graphically looked a bit bent and blood-splattered, but according to the durability gauge it was still top-notch. I don't know if this is a design flaw in the game or a deliberate mechanic, but whatever it is, it works.
My other criticism is some of the missions. Now, in this case, I have to say this is one scenario where having stationary NPC's give you instructions makes sense. There's a reason most of them won't venture out and take care of things themselves; there's fucking flesh-eating zombies out there! THEY aren't immune to whatever virus has caused this but YOU are, so guess who it would make more sense to send out exploring?
So while keeping the NPC's in one spot makes sense since the scenario is supposed to be people hiding from slathering undead, some of the missions they send you on seem really stupid. Collecting supplies? Makes sense. Repair power sources to signal for help? Good idea. Go fetch some personal nick-nack left behind in a hotel room or collect money for you? Are you insane or do you just have really fucked-up priorities?
Simply put, I'd say Dead Island isn't anything revolutionary in gaming, and simply puts together a bunch of tried-and-true game mechanics together in a zombie apocalypse setting. It works in some areas and doesn't in others, so I'd say playing through this to the end is worth doing, but I don't see this game having any sort of replay value.