Writing for Doctor Who is akin to being asked to do a run on Batman, Spiderman, Star Trek, or other huge, famous, and successful franchise (Gaiman is certainly familiar with the stress of writing for such a franchise). The "safe" route for a Batman story is to simply have a villain, some plot twists, and Batman being a brooding detective. Tinkering with the core mythos (Let's give Alfred a cocaine addiction!) is riskier - non-fans of Batman will not even notice this drift from canon, but the hard-core fans could hate you forever. But, if you pull it off (Miller's Dark Knight Returns, for example) then you add to the mythos, and you gain fame and fortune at the next ComicCon.

Now, "The Doctor's Wife" isn't as ambitious as The Dark Knight Returns, but the Doctor Who mythos is in a lot of respects tighter and more seriously followed then Batman's checkered continuity. But Gaiman does tinker with the mythos - and does so with typical panache.

Continued Below...

As long-time Who fans will attest, the Doctor's first love is the TARDIS. Human (and non-human) companions come and go, but the TARDIS is always there. And although the Doctor appears to be "in charge" of things, it's been clear since the start of the show that the TARDIS has a mind of her own, doesn't always listen, and in many respects is much, much smarter then the Doctor. It's been well-established that, while the TARDIS doesn't always take the Doctor where he wants to go, it does take him where he needs to go. Oh, and she's not a fan of the Chameleon Unit.

So Gaiman writes enough of a plot (and invents a villain) just to accomplish one thing - take the TARDIS, give her a humanoid-female form, and let her and the Doctor interact directly in a much more intimate and verbal manner. And trust me, watching the episode, you don't care about anything else - of course the villain is evil, powerful, and eventually stopped by the Doctor. Of course the supporting cast are entertaining and fantastic, of course the visual effects and set dressing are top notch.(The set design and dressing in this episode is simply amazing). But all of that is background. Yep - the certain death of our heros, the explosions, and race to exit a collapsing pocket universe, all of it is background.