There's a lovely callback to the show's first ever episode when Lestrade makes a small appearance at the end of The Final Problem.
When he catches one of his officers staring at Sherlock, Lestrade asks him why. "Well, he's a great man," the PC replies. "No, he's better than that," says Greg. "He's a good one."
Back in A Study in Pink, John asked Lestrade about Sherlock. At the time he said: "Sherlock Holmes is a great man. And one day, if we're very, very lucky, he might even be a good one."
The clear implication is that this day has finally come, and that Sherlock's journey from high-functioning sociopath to hero is now complete.
Only A Real Sheldon Fan Will Get 100% On This Big Bang Theory Quiz
Doctor Who: Why Every Doctor Left The Show
Friends Quiz: Who Kissed Who?
Spewing words on the internet daily. You can also read my stuff at StarburstMagazine.Com, WeGotThisCovered and TheQuiz.Com.