"The Case of the Cunningham Heritage" is the introduction to Sheldon Reynolds' series of half-hour Sherlock Holmes stories starring Ronald Howard, and according to the credits Reynolds Himself wrote this one. It's opening scenes, based not-too-tightly on the Conan Doyle story "A Study in Scarlet" are very pleasant viewing and give a good, compact introduction to this series' versions of Holmes and Dr. Watson. It's appropriate that this series, with Ronald Howard and a more enthusiastic and energetic Holmes, should start with him and Watson in their younger days. H. Marion Crawford gives a good performance as his likable, bluff, and competent Watson encountering the bizarre Holmes for the first time.
Adapting from a novel at the beginning in such time constraints, however, seems to necessitate the use of narration by Watson; it doesn't integrate well and seems to reduce the sense of immediacy on screen. The mystery itself suffers from being rushed due to the time spent on introducing Holmes and Watson, so we get the bare bones of the mechanics of the crime and solution without much character involvement. What there is is played very straight, to the point of slightly silly melodrama. In the scene in which the suspected murder was pleading her innocence, I actually thought it was going to be revealed that the story involved characters who were appearing in a local amateur theatrical production. We also get a good introduction to this series' extra-incompetent and temperamental version of Inspector Lestrade. His over-the-top character -- the series -- have usually seemed to work better for me so far when they don't take themselves too seriously.
On the whole this isn't a bad episode, but mainly good as a pleasant hello to the two stars of this "Sherlock Holmes" series rather than as a representative episode in itself.