This was in our household’s consensus opinion pretty much not a good followup to the season opener. Which is a shame, because we like Capaldi, and we’re now hoping he’s not going to be wasted on inferior scripts.
My main beef with it? I’ve been hearing rumblings going around about how this season is supposed to be darker, and how this Doctor is supposed to be more morally ambiguous–except the questions raised in this episode are all questions we’ve seen raised before in far better episodes. And not to mention that we’ve seen the whole “shrinking down to go inside something” plot before. Hell, this thing even namechecked Fantastic Voyage!
Spoilers behind the fold!
(ETA: And oh hey, Dara’s got her own reaction post up. That she has chosen to illustrate her points with screencaps from Lost in Space pretty much sums up what you can expect in her reaction!)