Writing for "Doctor Who Bulletin" in 1988, Jonathan Way felt the serial was fun, and for the same publication, Robert Cope praised Baker's performance as the new Doctor, also noting that the relationship between Baker's Doctor and Sladen's Sarah worked well. David J. Howe and Stephen James Walker, writing in "The Television Companion", admired the performances of Nicholas Courtney and Elisabeth Sladen and felt Marter's debut as Harry Sullivan was promising. They also commended the K1 robot costume, but criticised the use of CSO (colour-separation overlay) effects for a number of shots involving the K1 robot, as did Robert Cope. In "Doctor Who Episode by Episode", Ray Dexter described Baker's "over-the-top" performance as "compelling" but the plot as "a little lazy and derivative, with some terrible science." He considered the dialogue "some of the best we've seen" but added that "the story falls into the typical Dicks trap of just having baddies being bad because they're bad, and a logical robot behaving utterly illogically". He also thought the location work on video "cheapens the look of the show" and criticised the effects as "not good enough, not even for this era".