Spoilers for the third (or fourth, depending on your POV) installment of "Jekyll" coming up just as soon as I buy a new TV set...
Moffat's experiments with time continue as the bulk of the episode is devoted to the history of Tom Jackman and his hairy-armed alter ego. Even the present-day framing scenes are all about the question of Tom's origins.
Moffat wrote "Coupling," so he obviously knows his way around the romantic comedy aspects of Tom and Claire's early courtship. ("What do you do?" "Rich men... Sorry. It's a joke... Sorry.") I also continue to be impressed by Gina Bellman's non-Jane-ness, particularly when she's being flirty and having blunt conversations about sex, though that's mostly because I'd never seen her do anything else before this. (To use the obvious "Friends" comparison, Lisa Kudrow's proved she can do a lot more than Phoebe.) And in the present-day, she had the awesome coffee-tossing moment, so I'm a large fan of hers right now.
While not much is accomplished in the Peter/Miranda Callendar scenes other than establishing what Tom isn't, the flashbacks are an essential component to the larger story. Given what's coming, we need to be invested in Tom and Claire's relationship, and we also needed a broader view of how Tom started becoming Hyde. It's a bridge chapter, but a necessary one, and an entertaining one.
What did everybody else think?