Fallout 3 + Dead Rising + Left 4 Dead = Colour me impressed
If you love side questing in the spirit of games like Oblivion and Fallout 3, theres plenty of this to be found here. Throughout the world there are many hubs, each of which hold around 10-15 side quests, most of which feature multiple levels. If you don't rush the main quest, you can easily get around 30 hours out of a single play through.
Also, if you like the frantic zombie slaying of dead rising, you might like this one too, even though Dead Island focuses a little more on the survival aspect than on the mere pleasure of killing zombies. Yes you can customize and therefore improve your weapons, but its not as over the top as it is in dead rising. You need good weapons to survive, not just for the hell of it.
Finally, theres coop. Every quest can be played cooperatively, and you can have multiple characters. When theres someone nearby, playing the same quest as you are, or being around the same level, you can join with just the push of a button.
Technically the game certainly looks nice, but is not too flashy. When you load a game or enter a new area theres a lot of texture pop in, and the game looks a bit washed overall. On the other hand the framerate is steady even with lots of enemies on screen.
As theres reports of game breaking bugs everywhere: I'm in the middle of my second play through and I've encountered none so far. Ive been able to complete all my quests and the game didn't crash even once.
So if this is your type of game, and you can get one or two friends to give the game a shot as well this might just be for you!