This one series makes the purchase of YoutubeRED all the more worth it. It combines on the spot reactions from the cast and scripted events in an unholy mashup that works so well. Each season is really well put together and builds on the mythos of the last.
(Spoilers from here on out!!!)
The way that the lore builds is actually really believable, starting with the evil estate, The rise of a sorceress, the town called Everlock and a collector who saves dead souls for a collection. Just reading it sounds like an incoherent mess of a storyline, but it really works. There is a structure to each episode that works really well as well. It will start with the characters finding clues, turning on one another, voting people into challenges, and eventually, somebody dies. The fact that almost every episode follows this structure makes the twist endings in some episodes even more surprising.
Each season also ends with a cliffhanger, leaving you eagerly awaiting the next season. The first season ends with Joey leaving the house, with the deed in hand, the second ends with Joey dead, the third ends with a character we know to be dead pleading with Joey through a crystal and the forth ends with Joey trapped inside Pandora's Box.
The cast is great too. Each season (With the exception of All-Stars) brought new, interesting characters into the game. Who could forget the chill nature of Timothy DeLagheto, or the comedic moments brought by Glozelle?
In short, this show is well worth your time, bringing the best aspects of reality TV together in an interesting plot with fun characters.