Not as cohesive or frightening, as the first [REC] (which is one of my favorite modern horror movies), but still a tense and thrilling horror ride, more often than not. This is a direct continuation of the original, and happens in and around the same apartment building on the same night.
[REC] 2 takes the supernatural elements of the first movie and further explores them, which sets it apart from some similar zombie-type films. No complaints from me there, I enjoyed the expansion of the overall mythos and the added backstory/explanation for some of the people and events of the first film. On the negative side, I did find the new characters introduced in this one to be almost universally unlikable and annoying. Did that ruin the movie? No, but I definitely cared about the well-being and survival of these people less than those that came before. There's also a slight feeling of repetition that comes with using the same location again, but that's understandable considering the direct plot continuance.
[REC] 2 is basically more of the same, so if you enjoyed the first, there's no real reason why you shouldn't see this. It's not quite up to the same quality, but it's worth checking out to see the interesting direction the story goes in.