Really enjoyed this episode, and the last episode as well actually.
When they're not working really hard to shoehorn in series-arc clues and 'clever' clues and plots devices and twists for the sake of there being twists, then by-and-large the episodes are pretty good.
Obviously I don't include the Rings of Akhaten in that, that was complete garbage from pretty much whatever angle you looked at it.
Loved the monsters in tonight's episodes, they were suitably grotesque and when there was a cut to a shot of it right behind the Doctor I jumped a bit! (Maybe I just scare easily).
This series is finally beginning to get back onto form. Who is back!