I had mixed feelings on "Step Nine."
Good: the episode didn't use "London Calling," which is the cliched song whenever an American series crosses the Pond. I'm not sure "Hello" by Oasis was any better. Britpop, really? You'd think we'd traveled back in time to 1995.
Bad: I didn't really care about Lestrade, how Holmes left him hanging, how his life had gone downhill. It wasn't Pertwee's fault. The script had other things going, and it let us down there.
Good: Watson in the ersatz Batgirl t-shirt. That was a fantasy I didn't even know I had.
Bad: Holmes' jealous rant when Watson says Mycroft wants to take her to dinner.
Good: Rhys Ifans. He had good material to work with and I totally bought him as Holmes' older brother. (Speaking of which, I loved the call back to "The Greek Interpreter" with Watson's exasperation at the discovery that Holmes had an older brother.) I wish he were a bit more canonical, but for all we know at this point he really does work for the British government and his restaurant business is, like Universal Export for James Bond, a front for his other activities.
Bad: The pointless destruction at the end. I'm not sure why that was necessary, I'm not clear how that's supposed to get Sherlock's attention. It was random.
Good: The mystery. I was glad the episode didn't give us red herrings or blind alleys. We started from the assumption that the guy had done it, and then it was a matter of Holmes figuring out how it was done.
Also good: Watson stopping the pigeon guy in Washington Square Park. I'd like to think she used baritsu.
Overall I enjoyed "Step Nine." The Lestrade stuff, no offense to Pertwee, was the episode's main stumbling block. The rest was solid, and hopefully we'll see Mycroft again.