Oh, I'm completely with you on the character exploration thing - it's one of the things I've absolutely adored about RTD's era. But like I've said to skywaterblue below, I can understand it, but I don't feel it, and I thought that perhaps I was missing something really obvious.

And it explores what it means to be a time traveller,

Yes, which is something I'd not picked up on about Moff's episodes until whoever it was on that commentary I mentioned pointed it out! I can be dense sometimes *g*!

Midnight is one of my favourites, too.