BBC's Sherlock is a masterpiece. No argument there.
My complaint is: Why do I have to buy the whole season pass to get just the aired episode that I want, like how all other episodes of Sherlock have on iTunes?!
I NEVER watch the extra content on any piece, and I won't even do that for masterpieces like BBC's Sherlock. For me, they take away from the magic of the ACTUAL STORY. Yes, it's great for fans and it does add some trivia knowledge for watching the piece, but showing the sets, lighting, crew, ..etc take away from the magic.
If other people like BTS & interviews and they want to purchase it, great! Just don't force me to buy multiple "episodes" when I only want 1.