A number of people have commented negatively on this film, and also slam Rowan and Martin, Laugh-In, and the fact that this movie was made in 1969 and is therefore dated. I wonder why they bothered watching it.
I was but a toddler when Laugh-In was on, but I watched it with my older siblings. I've seen clips from it more recently, and yes, it is horribly dated now. So are bell bottoms, peace signs, and harvest gold appliances, but they were very popular at the time. People seem to have a hard time believing that something they really like today will ever look ridiculous, but it happens to every generation.
This movie is not particularly dated. Maybe 3 lines will go over your head if you have no knowledge of Sixties culture. This film is a silly spoof of monster/mystery films. Rowan and Martin act a lot like Hope and Crosby in their "Road" pictures, without any singing, and even speaking to the audience and acknowledging that they are in a movie. Every cliché from the aforementioned genres is skewered in this film, and I think it accomplishes everything it sets out to do.
You don't need to know anything about Laugh-In, Rowan & Martin, or the Sixties to enjoy this film. If you've ever enjoyed, or enjoyed groaning at, movies about werewolves, vampires, old houses, hidden treasures, and dead bodies appearing unexpectedly, you will get a laugh out of this movie. Personally, I watched it expecting the worst, and was very pleasantly surprised.