This is not the kind of movie where plot matters. It isn't nice to cheat Mr. Death, and death comes looking for them, one by one. Timing is everything in a film like this, and exaggeration is essential. You know someone is going to die, but it has to come at the moment you least expect it. Then, in retrospect, the moment has to seem exactly right.
Most critics treat all such movies with equal contempt.
Ebert liked this one, but Ebert has the advantage of having been an SF fan while he was growing up. In the view of the archetypical film critic, there are only two virtues in a film. Characterization is one. The other is obscurity. A critic loves a film that he is the only one smart enough to appreciate.