I agree that part of the appeal of this Sherlock has been the modern setting. As a Londoner, I recognise my own manor. The Victorian setting made it just like so many other adaptations. Also, the venue for the plot, a mansion in the country, also seemed too traditional. The Guy Ritchie films have given us a violent yet vibrant Victorian London, with life in all its sordid forms. The setting for his films are also part of their appeal.
Once Sherlock fell asleep for the second time on the plane I was confused, and the plot seemed to drift.