Having watched season 1 and the first episode of season 2 of Sherlock, I absolutely love the show, although 2×01 was very weird; very slow, very drawn-out, you think they’ve wrapped it up then discover that it was just the beginning. A bit like those games I shall not name where you play for 20 or 30 hours before you realize that was just the tutorial.
As a long-time Sherlock Holmes fan who has read all the stories and all four novels at least twice, I was very impressed by how faithful they managed to remain to the original despite moving it 120 years forward in time. All the episodes I’ve seen so far stick fairly close to the plot of one or two of the original stories, with a load of (often tongue-in-cheek) references to others.
The greatest departures I’ve seen so far are in the secondary characters: Mycroft is less sedentary than in the original stories, Moriarty is younger and crazier, and Lestrade is far more likeable and far more respectful of Holmes’s intellect and methods (the original character is described in very unflattering terms and is often resentful of Holmes’s success and not above taking the credit for Holmes’s work).
Many self-proclaimed Sherlock Holmes fan are very critical of this series and of the Guy Ritchie movies. I disagree; I suspect that their dissatisfaction stems from a skewed view of Holmes, from reading the original text through the lens of an interminable series of movies and TV series where Holmes is depicted as an elderly, pot-bellied, gray-haired upper-class gentleman. In that respect, they’re not unlike those Hunger Games fans who were shocked to see so many dark-skinned actors in the movie, despite the fact that the characters they portray are described as such in the novels.
The Guy Ritchie movies are obviously a reimagining rather than an adaptation, bearing little relationship to the plot of any of the original stories, but I think they’re quite faithful to the spirit of Sherlock Holmes. Their pace is obviously much faster, but that is Ritchie’s signature—cf. Tom Lehrer’s brilliant take on Oh My Darling, Clementine.