Simply brilliant!
The outstanding intelligence of Sir Arthur Conan Doyle's classic character - Holmes, the Baker Street sleuth - seems to have spread across this game. The examination -> deduction -> conclusion system is quite challenging, along with the little riddles that need being solved from time to time. I've also found the characters interesting, as well as the late 19th century London, where everything takes place. The only aspect rather silly is that nearly every woman back then was a prostitute...
Playing "Sherlock Holmes vs. Jack the Ripper" has been a very entertaining and stimulating activity. I give it a 10, simply for the fascinating intelligence with which the action develops.