I also like that rather than calling him a machine, John tells Sherlock he doesn't have a heart. Which is a nice call back to The Great Game when it's Sherlock himself who says that he doesn't have a heart.

Yes, that is very interesting. I actually like that better than John calling him a machine, because it underscores the fact that John is his heart.

John going to Baker Street rather than the hospital really doesn’t make sense, you’re right. I think of it that he went there to get her some clothes or something on the way to the hospital. Or to see the scene of the crime or deal with the police there. But really it’s just to have him be there to see the assassin.