Dead Island
I actually loved the first one, although that original trailer probably built up the game too much for some people.
Enjoyed the length of it and the weapons and even the story wasn't horrible.
Haven't read anything about Riptide yet, might have to pick it up. Why do they have to release so many good sounding games right at the end of the generation?!
How can a game that by definition is improved on be more mediocre than the original? Reviews like that don't make any sense which is why I don't bother reading reviews any more. It comes down to whether you liked the first game or not. If you did, you'll like this one. If you didn't, well... why would you think you'd like this? It's still the same game, just new story.