My review of the previous episode: The Lie of the Land.
To be one of New Who's longest-serving writers, Mark Gatiss really isn't all that impressive. He's turned in the occasional good episode(The Unquiet Dead is good, and I have an irrational soft spot for Robin of Sherwood), but most of his installments are just mediocre or genuinely bad (Sleep No More, I'm looking at you). Empress of Mars is a pretty basic Gatiss episode, in that it's just...there.