Sherlock has an interesting structure where you have 3 episodes but each in a feature film length which makes for good viewing and allows in depth case-stories in each episode. Season 1 is a great setup for a phenomenal season 2 . Season 3 packs a strong punch too. Season 4 is where it gets absolutely absurd as the storyline feels soap opera-ish and out of control. I'd have given a 9/10 if they didn't come out with such a horrible storyline in season 4.