Overall, nice episode... Although I saw the Doctor clone coming and I imagine there will be an Amy/Rory one as well which will make things interesting. I'm also liking how Rory hasn't yet died and he's breaking away a little from Amy - we're so used to seeing him running around after Amy and now she's feeling it instead (that said, who wouldn't if your husband ran after some plastic-y, clone-y thing?!).
I also noticed a rather tenuous link between when Jennifer was describing a girl (presumably her real self as a child) as wearing red boots. It's interesting that young Amelia Pond was also wearing red wellies in the Eleventh Hour. Probably too tenuous-a-link though.
And obviously, the continuation of the pregnancy/lady in the wall theme tune is interesting. I like how she keeps appearing as if she's pulling back a wooden window.
Also, I wonder whether all the music (Supermassive Black Hole and You Don't Have To Say You Love Me x 2) has any significance?
EDIT: I'm just thinking about how the Doctor ever became a ganger. Any speculation on this?