After thinking about it a bit more and reading others peoples comments I agree that the episode was a bit silly. The 'Paternoster Gang' (Strax, Vastra and Jenny) have completely overstayed their welcome to me- and seriously Moffat, we get it, they're lesbians!
I hope we don't see any more of them this season (or at all really) because I'm getting tired of the Victorian setting and I don't think Capaldi's doctor is a such a good fit for those 3. If Moffat really wants to keep them, he should make a spinoff show- it could replace Sarah Jane Adventures- or put mini episodes online, just as long as he keeps them out of the show.
I also don't think the monsters of this episode were particularly effective. Though I appreciated the references to Madame de Pompadour, it meant the droids weren't very original, there wasn't much motivation for their actions and less story than in the Girl in the Fireplace.