Season 1:
8.5/10
Good story, decent characters, and interesting concept.
Season 2:
5.5/10
The only season which I didn't like very much. Lot of it felt like filler and the story was stale and unmemorable, characters were still decent. Overall, not bad but not great.
Season 3:
8/10
Plot was very interesting this time, although I think the dynamic between characters suffered a little, also didn't like the separation of Dustin and the main group.
Season 4:
9/10
I loved the new characters, and all the plot lines were very interesting, although it did feel a bit slow at times.