Kev, I thought the first hour of Insidious was pure gold. Then, they start showing Darth Maul as you say. The first time you see him you're like okay, kinda creepy. I forget at what point it turns, but I think it's when the kid is kidnapped. After that, and they bring in the mediums, the film goes straight to #!!*. But like the first hour? Chilling. It was amazing how the two parts of the movie are polar opposites in terms of quality. I was REALLY looking forward to it, and can still appreciate it's early efforts, it's just a lackluster finale.
I think the writers got fired halfway through and were replaced with ones from the Asylum film studio.