Though many criticize this story as being weak, it isn't that bad compared to what comes, and it is as good or better than many stories before. While it isn't an exceptional story, it's good, solid serial adventure. Much of the charm comes from good acting, an unusual story for Who, and excellent direction. The corny component of repetitive dancing, over acting, and hysterics doesn't hurt it as much as the lack of such elements hurts dull Who stories before or since. An emotional component is necessary when stories become a "tale of two rooms".
I loved seeing this again after 20 years.
The real treat for me was hearing the cast/crew commentary track. Davison, Waterhouse, Fielding, and Sutton were a very good set of personalities to work together, and you can hear their ease and familiarity in the commentary. They don't take the show seriously and it provides a warm commentary, similar to an afternoon in Davison's living room with old friends. I love how these four seem to know so much about the show through all eras, including the recent series. Though technical commentary is much more satisfying, such amiable commentary is a good second best. John Black, the director, was on the track, but he was too often set back by the banter of the cast. Blame throwing never showed up, unlike many commentaries during the Nathan-Turner era.
It's a pity the DVD production didn't include the familiar "making of" documentary included with many of the more recent DVDs.