Well, that was indeed a shocker!
No, not Ruby being evil and the cause of Sarah's mix of Parkinsons and Alzheimers, I mean the fact that it *wasn't* the Trickster, in an episode with "Sarah Jane Smith" in the story title - a fucking shocking (but most welcome) departure from the series formula!
A nice little episode, with a fun guest star, but might have worked better if they'd run Sarah's symptoms as a story arc throughout the season, building to this.
Still another 8/10 or so, making this both the best and most consistent season to date.