Bill Wallo has good post on the sometimes conflicting virtues of truth and justice in the Sherlock Holmes stories. Wallo touches on how sometimes Holmes would sacrifice justice for getting to the truth, showing how this compares with our modern day conflicts of the virtues in things like illegal seraches and seizures.
I began reading them in seventh grade, and I still think the Sherlock Holmes stories are heads above anything else in the detective genre. Where else will you find a reclusive intellectual chasing a goulish dog across the moor?