At it's worse, the game feels like a sterile adventure game with some pixel hunting that relies more on guess work than logic. At it's best it's a brilliant mix of reality with fiction.
The environments look surprisingly great with very high quality textures. The main thing that let the visuals down are the production values. You will see reused models and reused soundbites over and over. The actual main characters themselves (Watson and Holmes) fit the characters in the book well but still tend to be fairly boring.
The most interesting character is one who practically doesn't appear on screen. Jack the Ripper. The "less is more" approach works very well into creating a sense of mystery and discovery very few games manage to do well. The bread crumbs the game gives you as you gradually progress towards the conclusion feels reserved (in a good way).
The game features real victims but handles the subject tactfully and surprisingly accurately. The game does a great job of making you feel like a detective in this period of time investigating these gruesome crimes.
A few times while playing the game I was stumped. This was more due to guess work than logical puzzle solving. In this day and age of the internet it helped bypass annoying aspects of the game that have you running circles doing mundane tasks.
Is it a game worth your time? If you can forgive and get past the hiccups yes. Worth picking up on a steam sale imo.