Rented it a couple of days ago, probably will go ahead and keep it a couple more and try to finish it. I can't imagine it having much replay value after completing it, though I'd have to say the same for Left 4 Dead. I think this game is a lot better than Left 4 Dead tbh.
I suggest tuning down the stick sensitivity, I normally even like it at 8 on Call of Duty but the default on Dead Island is just ridiculous, I think this is really where a lot of the bad reviews are coming from. Once you get the sensitivity right and adjust to the controls they're actually pretty intuitive.
Once you get to the city it gets a bit more fun imo, especially with the guns. I wish there were more online modes though, and it's annoying that sometimes when you're playing coop and somebody leaves you might have to restart the mission.