Well, it was definitely a hoot. Though I've got to say that I suspected the twist early on. And by the time they started pouring on the clues about three quarters of the way through, I was certain of it. But none of that lessened the fun one iota. And using the Psycho house as the exterior was great fun as well. (That really had to add to things for the audience of the original airing.)
And while we're on the subject of this show, I definitely found it interesting that in the first season not only did two separate eps star William Shatner, but they starred William Shatner paired with Elizabeth Allen, and a future star of Gilligan's Island. The Hungry Glass starred Shatner, Allen, and Russell Johnson - and The Grim Reaper (which I also thought was quite good) starred Shatner, Allen, and Natalie Schafer. I suppose they liked the pairing of Shatner and Allen so much that they couldn't wait to pair them again. Or perhaps they were a couple at the time and they requested to work together again. Who knows? But the pairing doesn't seem coincidental, even if putting them with Johnson and Schafer had to be.