These are very faithful adaptations to the source material, containing almost exclusively Doyle's own words. Although there are many necessary compressions, there is very little additional material or substantial changes from the source material. The trick that the writer had to pull off was to decide which portions of each story to include, how to abridge the story in such a way as to manage to still tell the entire story.
One of the best part of the adaptation of A Study inScarlet is the way in which the long stretch in Utah is covered. In the original, Doyle tells this in as an omniscient narrator, while this adaptation makes the story more clearly as Jefferson's Hope's words. This enables the art to bounce back and forth between Hope telling the story, with reaction shots of Holmes and Watson, and the actual flashback scenes in Utah. The artist is then able to give us many "camera angles" from which to show this action, which makes it easier to read in graphic form than in Doyle's prose. This is a very good use of the sequential art medium, and is an example of using the form in a way that prose cannot be used.
The iconic meeting between Holmes and Watson is handled well, and the choices that the writer made in what to leave out and leave in made sense.
There is less "work" to be done in adapting The Sign of the Four, as the original story moves at a terrific pace and tells an entertaining tale, start to finish. The only part of the adaptation that I don't think I would have followed without the original fresh in my mind was the "blind alley" that the dog leads Holmes and Watson on. But other than that one scene, the story was easy to follow, and the adaptation very enjoyable.
It must be hard for an artist to have a "new take" on Holmes and Watson, who must have been portrayed more than a hundred times in various forms. I immediately liked the look of Watson, but it took me forty to fifty pages (each work is approximately 120 pages) to get used to this look of Holmes. I could not reference him to any other Holmes that I was used to seeing, but this is actually a testament to the strength of the character design. The artist also does a fine job distinguishing the many supporting and side characters that populate these books.
source: public library