Luckily, the regular cast are excellent and Who's success must in part be based on how well they work together. It's dramatic, spooky and a little surreal. A pervading mystery is building up rather nicely and in particular, Carole Ann Ford's Susan is perfectly suited as the focus of much of the intriguing puzzle. There's a certain literary and cinematic history of teenage girls being the focus of disturbances that mix the social and the supernatural. Susan has already seemed a little different as a character in previous episodes, with her recounting her alien origin and this strangeness is intensified in this episode. The Doctor's alien nature is manifested in William Hartnell's performance and this is complemented by Susan. You can imagine, looking back, that Who could have been a rather different show if Susan's alien nature had been written as large as the Doctor's.
The shots of the console room are wonderful and our pleasure is only enhanced in knowing that in recent years we have seen a remake of this console room in the new series. It might be a "bottle" episode but this is a highly enjoyable, exciting adventure nevertheless.