The Sign of the Four didn't interest me as much as the Study in Scarlet, even though the first half captivated me. I thought the lengthy back story at the end was long-winded, and I would have rather have had Holmes and Watson done some deducing and interviewing to figure it all out...rather than a sit by my side and let me tell you a long story.
The cocaine? It's not something I ever realized was a trait of Mr. Holmes, and in a way, I found it amusing by the matter-of-fact attitude it all went about. No wonder he has all that energy to solve all of these mysteries! I was surprised by how Watson reacted so negatively to it, when at the time, I don't think it was seen as particularly addicting.
Miss Morstrand was boring. We never got close time with Tonga, who would have been quite exciting and unruly, but we got a murder, a tracking dog, a boat chase, and a capture.