A reasonably interesting screenplay but it is unfortunately too long. However, there is compensation in that there is more time to admire the performance of Christopher Plummer.
Adding Olivier Gourmet into the mix and there are 3 fine actors who are used to carrying films on their own and are really the main reason for watching this screenplay.
Not all the scenes work but those that do should leave an impact. What can't be denied is its originality and the high standard of its special effects make it memorable.
When I first saw this in the 90s I thought it was okay, if overlong, but that it didn't offer anything new. A rewatch has done nothing to change that opinion.