Briefly, enjoyed the book. Love SciFi. Think Burt Lancaster, Barbara Carrera and Nigel Davenport do the best they can in this movie.
But (sorry, have to say "but") Michael York is definitely graduate of Hambone School of Overacting, like Ben Cross (remember "The Far Pavilions?). For my taste, he pretty much sucks the juice out of any scene he's in.
Combine with some script holes, and you've got a mediocre movie, which is still much better than the Marlon Brando/Val Kilmer version.