The game is visually stunning and manages to capture the atmosphere of late 19th century London and the surrounds extraordinarily well.
The visuals themselves are most definitely the greatest part of the game, and as a series of sequences of eye-candy the game tends to work rather well.
Where the game falls down is the actual gameplay, however. It is rather fun initially to run around sniffing out clues and talking to people, however this becomes repetitive rather quickly. There's very little available to actually challenge the player, as it's more or less a point-and-click to find the clues then these clues simply describe and fit themselves into the overall puzzle.
There were an entire range of different aspects that I would have rather focused on in each of the cases if it was a more free-world kind of game, however the game simply guides you towards conclusions. As a mental exercise the game is therefore practically worthless, which is a pity considering it is about one of the more intellectually gifted characters of the modern world.
The inability of the player to actually go wrong anywhere except in the final conclusion does rather reduce the level of reward the game can offer.
As a relaxing little piece of visuals flitting across your screen the game works well. However at $40 the price is rather steep. I would price the value of this game at about $15-$25, depending on what you're looking for. If you're more interested in nice visuals and atmospheric gameplay then you might be willing to fork out a bit.
If you're more interested in strong gameplay and a mental challenge rather pick up one of Paradox Intereactive's games for half the price, wait for this to go on sale (like, 50%-75%), or play a game of chess.