A few thoughts: As the fan of Hammer and sci-fi that I am, this movie sounded like a match made in Heaven just for me. And while I did enjoy it and found the premise clever and interesting enough to keep my attention, I wasn't as invested in this one as I thought I might be. This is an incredibly '60s film filled with all the slick set designs and technology found in classic Star Trek and Bond movies. The acting is passable and the pacing is solid (with a few sluggish and hokey moments), but it's in the end of the movie that the film really establishes itself as something uniquely special. This movie goes totally bonkers in the last 20 minutes or so, and in the best sort of way. Though it doesn't stand up too well against some of the better science fiction shows and movies of the time, it would ultimately be incredibly unfair to pit (PUN!!!) this one up against titans like Star Trek, so make sure to go in with your expectations tempered, fully aware of the clunkiness of the script and outlandish nature of the film's finale.
Who would I recommend it to? Fans of 1960s sci-fi and Hammer completionists should give this one a try, but the audience is pretty specific.