I've all all those bad reviews about Dead Island Riptide and I've seen so many bad reviews, but, hey I didn't get discouraged and I decided to give it a try.
The game mechanics is like the first one; you kill zombies you get upgrades. You can find money everywhere, that's why I think the game is easier than the previous one. The bosses can be beaten in few moves (and there aren't many of them). There are some NPCs along the way which you meet and help. You can same some for rewards.
You can repair your weapons if they get damaged and you can upgrade them sing different modifiers.
There are moments when you are overwhelmed by hordes of zombies, yet seldom, and with a little help from your companions you can take them down. There are lots of places to discover and too much loot and that's why the game seems too simple and too easy.
The soundtrack is awesome.