I thought that was possibly the weakest episode of the series so far, although it wasn't too bad.
Lots of holes in the plot, and not a terribly exciting or original storyline, but a few humorous bits and lines.
I'm still happy to keep on watching.
This week had a slight reference to the crack, purely verbally, I didn't see any actual cracks in anything in this episode.
It's hard to tell from the teaser at the end of the episode, but I wonder if the next episode will have any direct bearing upon the "crack in reality" storyline? When we had the Bad Wolf bits, it was quite subtle, and it wasn't until well through the series that we realised it kept on cropping up. With the crack, it's very unsubtle, and if they keep us waiting until the very end for any reasonable details, it's going to be a bit annoying.