This game is a bit of a departure from typical Holmes, as it mixes in a Lovecraftian element that gives the story an unearthly taste. I don't have a problem with that, but if you're not really a fan of sort of "out there" paranormal storie, you might not appreciate this game. However, even if you're not a Lovecraft fan, you might be engaged enough with the story to enjoy this too.
Gameplay is pretty standard pointy-clicky fare. As in most of these styles of game, the puzzles range from very basic to ridiculously difficult, but thankfully there is an in-game hint system that does help a lot to keep frustration to a minimum. The only truly difficult part I found was a point when you're in a dark area with a lantern and must find all the clues to progress; the last "piece" was very difficult to locate in the dark.
For mystery/detective fans who also are fans of Agatha Christie, there is a delightful "easter egg" partway through the game. As a Christie and Doyle fan, I squealed like a wee happy baby. I won't ruin it here, just keep your eyes and ears open for it. :D
My single real complaint (and it's just a nitpick really) is with the sound; there's a point where there are a lot of people using alert/warning whistles and they were piercingly loud (and over and over and over again, ouch my head). I didn't even have the sound up that loud but I thought my eardrums were going to rupture. Just a minor thing to keep in mind; you may want to keep the volume lower or even off when you hit that section.
So go grab the Sherlock Holmes Collection where you can get all six of the games at once and save a good bit of money. They're definitely worth it for fans of Doyle's Holmes.