The resolution of the cliffhanger from season one was thoroughly disappointing. But other than that the first episode is incredible, particularly the ending. Unfortunately, there are some content issues: there is a woman who spends several minutes on screen undressed. She covers herself with her hands or else the camera is conveniently placed to avoid showing too much. But in my opinion too much was still shown. Also, at some point this woman changes the ringtone on Sherlock's phone associated with her number to be the sound of a woman moaning in pleasure. This was a little much for my taste. Also, there are getting to be too many gay jokes about Sherlock and Watson. The other two episodes were enjoyable, but not as good as the season opener. The cliffhanger at the end of the third episode was predictable since I've read the story it's based on ("The Final Problem") and its sequel ("The Adventure of the Empty House").
 See my review here.
 If you watch this episode, avert your gaze when Sherlock goes to a woman's house and gets shown to a waiting room. Do not look back until she agrees to cover herself.
Big Ben at Night is by Historywriter, available at http://commons.wikimedia.org/wiki/File:Big Ben, Houses of Parliament, Wesminster Bridge @Night.jpg.