An amazing plot, killer graphs, and the hardest puzzles ever found in a game combine to make this title simply unique.
There is a warning to be made, though: This is for true, old-school, addicted adventure gamers, and casual puzzle solvers will either scream for a walkthrough or bang their heads against the keyboard at certain moments within the game. The solution of some puzzles will require a small notebook by your side, if not a calculator. That being said, the game's highlight, aside from its near-perfect plot, is the absolutely immense variety of puzzles this game. From old-school inventory based ones, to ridiculously hard riddles, to frustrating numerical challenges (I kind of missed that last one, lately), you'll most likely see smoke exiting your ears after being stuck for half an hour wondering what the hell are you supposed to do to open that iron door. That, in fact, is the game's only flaw: The puzzles are ridiculous, at time, and I'm not ashamed to admit that I searched for a walkthrough at a handful of points. I don't like walkthroughs, as I think you're only fooling yourself if you use it to finish a game, but several of the game's most challenging moments come with no background logic at all.
The graphics are simply incredible, both the environments and the characters. I can't remember full 3D environments as detailed as those of this game in any adventure game I've ever played, and the scenarios are simply stunning, both on its immense size and on the scale of its details. You'll literally spend hour after hour just watching the paintings at the Museum of Art, across Trafalgar Square, or going through every corner of the London Museum of History's library, and while the prospect might seem boring, it's one of the most pleasing aspects of the game.
The characters are well designed, both visually and in their voice acting. Each character 'looks' and 'sounds' unique, with their voice generally matching their looks. A fat ol' drunkard at the Golden Lion pub will sound uneducated and disrespectful. Lady Leomunda, the Queen's lovely companion, will sound well-raised and arrogant.
The gameplay is for the most part point-and-click. Though rather than moving from screen to screen, as in most adventure games, holding down the left mouse button will take you around the 3D scenarions (double clicking will make you run), with the cursor instantly changing to an eye, to look, or a hand, to operate, whenever you come near an object you can interact to.
So, while it WILL frustrate you, I can't bring myself to give this game a lower score. Why? Simply because of the sheer weight of the two main characters' name, and how well they both interact on this absolutely amazing and immersive plot. I can't help but call this a classic... If it was any easier, it wouldn't be a challenge worthy of Holmes and Lupin, and while the developers failed to deal with this difficulty (it'd be actually pretty easy... Just put a hint button or something of this sort), it steel feels better than any adventure game I've played lately.
Go get yourself a copy, just be ready to become frustrated, nothing that a little patience wouldn't fix.