I played the first Dead Island game, and quite enjoyed it, but found that guns were basically worthless against the zombies. Against humans they were useful, but they were worthless against zombies. You were far better off with melee weapons.

So, I'm wondering if this is basically the same deal in the Dying Light series, or whether guns are actually effective (albeit limited in ammo, as I'd expect)?

Guns are very effective in this game, but a) they are rare and b) they break after a while. This is my main gripe with this game by the way: Imho weapons break too fast.

Guns are very effective, though ammo is rare. Headshots are one shot-kills on zombies and humans, but enemies can take a lot of shots to the body. Guns are very useful when fighting humans, as they are very hard to fight with melee-weapons (they dodge a lot).

I don't think guns have durability in Dying Light. I've been using one rifle through my entire playthrough, and it has never broken.

Like in Dead Island, melee have durability but guns don't have it

But don't forget, using guns & explosive attract zombies ;)

Hm... I could swear I used a gun and I had to repair it. Gotta check that when I start another playthrough soon. Or did the devs changed this in a patch and I haven't noticed (yet)?

You can easily mod the durability of every weapon (or all of them at once). BTW guns/bows just use ammo, don't break.