Visually it's great. I am not a fan of controls, though: I believe it's not really convenient to run always holding left stick (I use gamepad) and using RB instead of A to jump.
Now... Comparison with Dead Island. There is actually one main difference between the two: level of seriousness. Dying Light takes a realistic-ish approach. Whole atmosphere is made to make it feel as real as possible: zombies are few compared to Dead Island, they are a bit more sluggish, but yet more bulky, you can feel their weight when hitting them. The colors are more grey, making the world look sterile and lonely, while Dead Island was bright, reminding you, that a few hours back it was brimming with life.
You also get into zombie fighting here, when other are fighting it for a long time already. Dead Island showed the start of infection, lack of knowledge and skills. Dying Light, shows what becomes of such fight in a few months, when it becomes a routine. It reminds me of Metro and S.T.A.L.K.E.R. games in this regard.
But then there is a dissonance. Secret agent infiltrating an organization on the matter of (yet?) incomplete cure? Come on, they all need the cure, so any concerns regarding it should be discussed openly, no? And where in real world does a noob prove himself in an organization as if it's an old-school RPG?
Overall, if you prefer a post-apocalyptic zombie game with a serious look and can ignore some minor issues with the story and story-telling - you may try this. If the above does not really appeal to you, skip. I am skipping it, because I'm just not in the mood for such seriousness at the moment.