Arguably the greatest horror/thriller series I've ever seen. I was expecting mild jumps with..just enough story to keep it going, but it brought so much more. Although the story jumps around from past to present, they do the transitions very well so you never feel like you're disconnected or have to reacclemate to the scene or characters.
I won't say too much but it was roller coaster for me and I've been watching horror movies since I was a kid. I wouldn't say it was the scariest thing I've ever seen, but it certainly takes first place as the best horror show I've seen.