I'd already figured out who the little girl really was less than halfway through the episode. Not because I'm a super smart sleuth like Sherlock is supposed to be, but because it was predictable.

Liked it (mostly) until the insulting and nose-thumbing ending. To basically make all the characters imaginary is a cheap, overused literally trick. And the do-it-yourself ending, add your own pizza topping? Infuriatingly lazy writing, a cop out. Was it real? Wasn't it? You decide! No, I didn't care by then.