I watched this film when it first came out on VHS (I think? It may have been DVD), already knowing the twist but with a few people who didn't, and didn't guess it either.
What surprised me was the film was much better than I remembered. The Riffing was great, but I found myself having to concentrate to avoid being drawn into the film so much that I mentally tuned the riffs out!
The only exception being that hideously clunky opening certificate scene. That was awful- you could have chosen almost any method of exposition and it would have been less cringeworthy- even an opening crawl! Although what with the credits being so long, you could argue we already had one of those.