Sherlock Holmes basically gave the world the entire CSI franchise. After all, Conan Doyle's fictional detective proved that people not only love detective fiction, but that they actually enjoy reading about a detective who uses science to solve crimes. And Holmes really was on the cutting edge of science in the 1890s. Forensics was in its infancy, and Sherlock Holmes's forays into handwriting analysis, fingerprinting, analyzing tire treads, examining shoe prints, and assessing blood stains were all signs of things to come in policing. Holmes doesn't just use scientific methods to solve crimes though. He also embraces science as a behavioral regime. Holmes is always cool, rational, logical, and efficient. He's like a Vulcan. For Holmes, being a scientist and a scientific detective meant favoring the mind over emotion, and crime solving skills over social skills.
Holmes takes scientific methods and reasoning to such extremes that he often comes across as a sort of robot and has trouble interacting with people on an emotional level.
Though Holmes talks a lot about being an always-logical scientist, he is often not all that "scientific" in his behavior: he's sometimes jealous, rash, impatient, and needy.