I think the subject of this particular episode has been a long time coming, as it finally addressed the issue of the love affair between the Doctor and the TARDIS. The fact that the TARDIS is the Doctor's one true love has been sitting underneath the surface for some time and it popped out in a big way.
In a nutshell, the plot thickens as the Doctor, companions and TARDIS are lured through nefarious means outside the universe (Yes, outside, and I'm with Rory on this one. How can you be outside the universe?) to a junkyard of all places. They land, and the TARDIS matrix is promptly sucked out of her little blue box.and into a woman. An evil entity/asteroid then steals the remains of the TARDIS, plus Rory and Amy. The Doctor and the TARDIS matrix then have to save everyone, including themselves, and that's when the real fun begins.
The interplay between the Doctor and the human TARDIS played perfectly, from her confession that she stole him, and not the other way around, to when they argue like an old married couple building a new ship. It was a serious of joyful and intimate scenes, where all (or at least some of) the truths came out.
And the other subplot of the episode reversed the dynamic between Rory and Amy as they try to survive in the TARDIS shell. Rory is the one in control and it's Amy's insecurities that make her vunerable. Rory (mostly) gets to to save the day. My favourite part was when the human TARDIS calls Rory "the pretty one".
Of course the Doctor and his TARDIS save the day, and sadly everything goes back to the way it was, with the matrix back inside the TARDIS. But you can't cork the bottle entirely, because after all, Doctor Who is essentially about a boy and his box who ran away to the stars. The rest of us just tag along for the ride.