Topping the previous instalment is common practice in fiction, and yet taking an already high-speed, brainy series up to the next level entails certain risks.
And sure enough, I found this a wee bit Too Much of everything. Holmes himself is approaching the Ross Geller-syndrome (turning into such a parody of himself it's hard to see why anyone would want to see him at all).
The plot at times is really more twisted than interesting.
Most of all, I felt the writers had been caught up in the trap beckoning many creators, especially of detective fiction,
i. e. the characters have grown so popular they take precedence over the plot (a.k.a the Elizabeth George-syndrome).
A bit disappointed therefore, tough it's still quality TV.