It is no secret regarding the various difficulties which occurred during the making of this "Sherlock Holmes" series. Original leading man, Douglas Wilmer, had left the series after having a falling out with the BBC.
By the time 13 more Holmes stories had been commissioned, Peter Cushing had stepped in to play the Baker Street sleuth. Consequently, he didn't retain overly fond memories of his time on the series.
"A Study in Scarlet" makes for marvellous viewing, in spite of the changes made from the original novel. The episode makes no reference to Watson being introduced to Holmes after having been demobbed from the army. However, the actual plot is quite accurately depicted.
Personally, I find Peter Cushing to be a superb Sherlock Holmes. Whilst I understand the actor was unhappy with his own performance, his usual solid professionalism is very much in evidence. He also manages to convey some of the character's personality traits: sudden impatience, pomposity regarding his own abilities, being a bit foolhardy at times etc.
The episode is one of only 6 that exist in the television archive (thanks a lot BBC!) but all are worth watching.