I rated series 1 - 8/10, series 2 - 9/10, series 3 - 9/10 and series 4 - 4/10; let me explain. Series 1 was getting established and was really good; the partnership of Benedict Cumberbatch and Martin Freeman was one of the most highly successful pairings in TV or film history. They were made for one another, and this didn't change throughout the four series. Writing, sets and direction were spot on.

Series 2 and 3 continued in a similar vein, being top-notch most of the time, with a few digressions. Superb viewing most of the time. Series 4 more or less kept the standards of acting and technical stuff very high, but the writing and direction went steeply downhill. Whereas previous series had taken a lot from the original Conon Doyle novels, for series 4 the writers seemed to disappear up their own backsides with some ridiculous and pretentious writing that would have been more appropriate in a Doctor Who series than Sherlock Holmes. I was not surprised to hear that both writers were involved in writing Doctor Who episodes at the same time as they were doing Sherlock. Success either went to their heads or they lost their way!

So that's my take on the Sherlock series. All well made and watcheable with my caveat that series 4 lost the (Sherlock) plot.