"Well, well, I suppose I shall have to compound a felony as usual."How do I love this quote? Let me count the ways!
-- Sherlock Holmes, "The Adventure of the Three Gables"
First, the general wryness is charming. Holmes is exhibiting what he referred to in Dr. Watson as "a certain pawky humor." One can almost hear him pause before saying "as usual," perhaps with a theatrical sigh.
Second, the way this quote refers to Holmes' past actions makes those familiar with the great detective's adventures feel right at home. We know from experience that he's not exaggerating -- Holmes really does compound felonies a lot.
In my recent read-through of the Canon, I counted four occasions on which he committed burglaries. (Legal hairsplitters say they were not burglaries under British law because no crime was intended, but to me they were burglaries.) I didn't count the numberous times he let the criminal go, but "The Adventure of the Blue Carbuncle," "The Crooked Man," and "The Adventure of the Abbey Grange" spring to mind.
Third, Holmes is clearly telling the truth here -- which he does not do when he claims in "The Adventure of the Illustrious Client" that "I use my head, not my heart." In every case in which he lets the villain go, he is doing it for a heart reason, not a head reason.
The frequent assertions of Sherlock Holmes that he is no more than a brain, an "ideal reasoner" may reflect his own self-understanding, but they do not reflect the reality. In truth, Holmes had a great heart as well as a great mind.