Another interesting episode. the show has always done these kind of period pieces well. I couldn't help thinking how impossibly lame the creature would have looked if they had tried doing this episode during the 1970's. CGI has really helped this show a lot.
Bill's concerns about slavery were an interesting touch - I imagine the Doctor will not be taking her to Mississippi in the 1850's any time soon.
A few old Doctor Who stand-bys in this. In Sutcliffe we have the human businessman who's a bigger monster than whatever actual "monster" the episode features, and of course, the old drunk who wanders off and gets eaten.
Overall: Another pretty good story.
The mention of slavery was long-overdue but at least a step in the right direction for a show that often glosses over such things or, worse, projects 20th century attitudes on socisal ills of the past ("Evolution of the Daleks in Manhattan").
I thought this was a step up from "Smile." Here we get to see the Companion shocked to discover that the Doctor's moral code doesn't necessarily line up perfectly with her own. This is one of those times when the New Who format works against the storytelling -- I'm OK with Bill ultimately accepting that his perspective is different from hers, but it would have been nice to see the conflict play out longer and with more detail. You could do that 90 minutes of story. But here, it's one speech and she's back on board.
I really did like this one, though, and I'm looking forward to hearing the Lad's reaction.