Absolutely love this show. Wasnt able to watch it last night but will catch up today. From what I've read they plotted out 5 seasons worth of content which I think is a bit of a stretch. The basic concept of the show is pretty basic but the way it's shown and the theories you can make up in your head are crazy.
I'm sure James Marsden is sick is getting killed 2-3 times in every episode so far though lol
To like it even more I'd recommend watching the 1973 version on which the show is based on.
http://www.imdb.com/title/tt0070909/