When I watched the first couple seasons of Sherlock, the BBC version, you know, with Benedict (Cumberbund) Cumberbatch and Martin Freeman, I was thrilled. Holmes was such an intriguing character. He was witty, arrogant, funny, and always right even when it seemed like he wasn't. Then season two ended with Sherlock's "death." And of course, anyone who was anyone knew Sherlock hadn't actually died because--well, the show must go on.
I approached season three with great excitement only to find the reasoning for Sherlock's faked death was awful. It was solely for Watson's benefit, and so complex and ridiculous it strained verisimilitude. Oh, that and the main bad guy, Moriarty died at the end of that season also.
Season three was a horrible disappointment as Sherlock yearns to discover who Watson's to be bride is, and (surprise) she's a secret agent.
Sherlock goes from an awesome detective, skilled in deduction, to a petty man-child who's jealous of his friend for being in a relationship. And not only is a whole season dedicated to this, but it spills into season four.
At the end of season three Sherlock shoots someone in the face and kills them--Sherlock is arrested and seems to be off to jail, just before a message from the departed Moriarty pops up in the British government's computer system. They release Sherlock so he can discover what's going on. This, unfortunately, takes all the tension out of the series, as consequences simply don't apply to the protagonist of this piece.
In season four--it doesn't get any better. In fact, it continues its downward spiral. Watson's wife dies, which makes all of season three pretty inconsequential, and then the second episode is just Sherlock trying to win Watson's trust back--something we've seen before in season two. The final episode, which had an intriguing set up, was, in the end, cheesy in the extreme and horribly contrived.
When Sherlock finds out he has a sister who is also a prodigy, he gains access to where she has been held, a prison, only to find she's taken control of said prison. She puts Mycroft, Sherlock, and Watson through a series of tests, only in the end to be forgiven for killing a ton of people because, you know, Family.
Sorry for the spoilers, but I needed to vent. This series had such potential the first two seasons, and now--"utter rubbish," as Sherlock would say.