I playtested it. It was very, very fun.
I'll talk a bit about the investigator-less Scenario 5: the plot is that the sun is going down and the investigators have to survive the night. When my wife and I played, Hurricane Sandy had just swept through and our power was out! We used an LED lantern and turned it dimmer and dimmer as the turns wore on. The effect was awesome.
Anyway, we were playing the bonus map (Scenario 5 has two different maps you can use), and I had found the key to the cave. I concluded that we could take shelter for the number of turns that remained, and the monsters would be unable to catch up to us before we won.
Scenario 5 has Mania cards. These cards are drawn whenever an investigator goes insane, or during other random events. A Mania card dictates a new restriction on the way the investigator can win the scenario (instead of merely "survive until the last turn," for example, a card could say, "you must be in an indoor space," or, "you cannot be in the same room as any other investigators"), and has a "Reflex" ability that triggers randomly each turn. Her Mania card was one of the Pyromaniac cards, so she was randomly setting spaces on fire! She (Dexter Drake) had managed to damage herself severely and was down to 1 stamina. I bolted for the cave door, the Cave Entrance was 2 spaces away from her and was still locked so she had a spare action. Naturally, she chose to explore. What did she find? A DITCH in the ground! She fell in, losing her remaining stamina, and was eliminated.
I (Bob Jenkins, the only investigator who had not been played yet) holed up in the cave until sunrise and won the game. It was the first time I had ever won a Mansions scenario as an investigator! Too bad I was all alone.
All five scenarios are interesting and unique, and none of them are wholly reminiscent of the linear-clue style predecessor scenarios.