Although the game consistently evokes Victorian London just as Holmes would have seen it, thanks to Bob Bates' intensive research and writing excellence, Sherlock doesn't really succeed as a game. For starters, the game's excuse for not letting you play the famous detective himself is a bit illogical: Holmes turns the investigation to you, Watson, because he wants to throw the villain off guard (riddles left at the scene of the crime include a direct challenge to Holmes, who suspects a deadly trap). Much of the game involves travelling all over London (and there are dozens of places you can go right away, adding to the confusion) to find similar objects whose use won't become apparent until the last portion of the game. The riddle which the thief left at the scene serves as the game's "meta-puzzle" and overall direction of what you should be doing next, but most gamers will probably find it too obscure. Most disappointingly, Holmes rarely interacts with you in the game, and since must puzzles resemble a scavenger hunt, there is no room for Holmes to display his legendary deductive powers.
Overall, I was quite disappointed with Riddle of Crown Jewels. Sure, it's fun to travel around London, reading excellent descriptions of various locations, and listening to authentic Victorian dialogues. But at the end of the day, it's the game that matters. The game will probably appeal only to IF experts and die-hard Holmesians who can decipher a huge amount of obscure puzzles. For a more accessible Holmesian game (although admittedly not as true to his mythos), try Bantam's Another Bow or EA's Lost Files of Sherlock Holmes instead.