Interesting characters, engaging plot, good sense of drama - what more could you want.
Watching this episode made me feel nostalgic about my childhood, because I am old enough to have watched the original. William Hartnell did an excellent job when he created the role of the Doctor; and his companions, played by William Russell and Jacqueline Hill, were shown as mature, sensible people with good ideas of their own. Although the sets reflect the low cost nature of the production I was surprised how little this effected my enjoyment.