If it's not broke don't fix it.
This is totally the case for Paranormal Activity 2 which is more or less a carbon copy of the original but still adds so much to make it stand out on its own. Just like when I saw the original I was getting super nervous to watch this expecting it to be the scariest thing ever. Although it didn't reach up to scariest ever it still had my blood pumping and thoughts racing. I really enjoyed this movie a lot more than I originally thought mainly because it did something most sequels don't accomplish by giving it's predecessor a run for it's money.
Also the way the film was marketed gave it a total sequel feel but what caught me off guard was this movie was a combination of prequel and sequel. I totally had no idea but loved the idea of getting a little more into the characters than compared to the original which just threw you right into the story. With this film being majority prequel it actually makes the original a little bit better and defiantly makes me want to watch it again.