Quite risible (spoilers)
I'll admit this had me intrigued and entertained for most of its length. But gradually I came to see that surely it's just plain daft, the number of plotholes. I mean, a brother is meant to die on a certain day, and is fretful because it's the day itself! What is Holmes doing? Faffing about the nature museum in Kensington to find out what kind of bird is on the cryptic drawing! Meanwhile the brother is encouraged to go home to be safe, taking a solitary walk through dark and foggy Victorian London!
Holmes often is plain cavalier regarding his clients' welfare. What's more, the finale doesn't make sense! It appears that the boyfriend has been killed, but oh no he hasn't been, and he and the girl are going to get married! And if the boyfriend is innocent all along, then his sending the brother home through the fog and total lack of sympathy make him a rotter!
And what's more, the note is similar to one sent 10 years ago, marking the death of the girl's father. Was Moriaty involved in that too? If so, it's a long time in the planning.
At times I felt this film might have been aimed at 10 year olds.