It's fun if you're a fan of melee combat, but if you're expecting big changes in the series, you're in for some disappointment.
The original Dead Island managed to set a good precedent for the team at Deep Silver. Not only did it get a lot of attention with an innovative debut trailer, but the game itself was quite good, with the sort of melee combat that was missing from other first person ventures. Still, the game was far from perfect, especially when it came to repetitive combat and stale textures that made the tropical island you were stuck on less than resort-worthy.
So now we have the sequel, or rather better termed as a follow-up, as Dead Island: Riptide doesn't really feel like a Dead Island 2. Rather, it's a continuation of the first game with very little improvements, and some folks expecting "the next big thing" are likely to be disappointed. There's still plenty to like here, especially when it comes to setting gory traps that spill more blood than an Eli Roth exhibit, but you can't help but think more push could've been given for this continuation so it could've actually been considered a sequel.
The story picks up following the events of the first game, with the survivors ending up on a freighter where, surprise, more zombie madness breaks out. Following that, the crew end up on another island, with a new survivor in tow, where they run into several others and complete quests in an effort to survive. Some are mere fetch quests, like the first game; while others involve you playing on a strategic angle, setting traps and defenses for incoming waves of zombies.
