There are a few camera effects used and general setting choices made to enhance the setting, not everybody likes movies that do this. generally blues and grays are used heavily, however this does enhance the movie for me, and it may for you as well.
So, no spoilers here, I saw it in the theaters, I don't bother to see something in theaters unless it crosses a certian threshold, specifically it must be an action film of sorts (because comedy looks just as good on a TV/PC), it must have a plot, it must not involve one Uwe Boll (of bad video game film fame) or be directly derived from a video game (where if you have played the game you have seen the movie), etc. Most of the movies that qualify are worth seeing once, and perhaps a rental/borrow from library/stream/whatever
about 1 in 20 surpass this threshold and become movies you MUST have on Blu-Ray for the quality... etc. So, trust me, this is one of the exceedingly rare movies where the plot, acting, action,camera is solid and comes together well. In addition the special features are very good, alot of the reaserch (and you have to do some for a film like this) is shown and some amusing people are met (sherlock conventions, who knew?)
So again, until the store closed as a casualty of Netflix in the mid 2000's I rented out movies, I saw numerous movies for free as a perk of the job, I know what makes a movie worth seeing more than just twice, more than three times really. This movie has that something... so do the other movies I recommend below (Equilibrium and Taken are among the best two action films I have ever seen, I discovered Equilibrium during my tenure in the twilight of movie-rental-storedom)