In an article for the Guardian, Terry Pratchett's done a nice comfortable writeup of his enjoyment of our favourite show for the last fifty years.

"I was there at the beginning. That's what I remember – watching the first episode twice, because of public demand and that pesky business with the grassy knoll. And I remember the dreadful pepperpots appearing, and the moment that the first companions left – that strange grandchild and those remarkable and rare teachers who took everything in their stride, including time travel and a police box bigger on the inside – and we realised that in the so‑far surprisingly safe world of Doctor Who things could change. They were barely mentioned again, as far as I remember. And the series marched on. Until the great defining moment, the decision that would propel the series on for 50 years – the change of the main character, the first regeneration. It's easy to forget now how groundbreaking that moment was. Our hero dies – and the series continues, a different lead with different tics but somehow still the same man."

And so forth. It's rather more laid-back and pleased than the last time Pratchett was talking about DW (back in 2010, when a similar piece for SFX was twisted by lots of headline-writers into "Pratchett Hates DW!" and so forth when the main thrust of that article was simply that DW isn't SF. Not at all an unreasonable argument, especially the same year that Moffat and the BBC's publicity machine was hyping the faery tale line. That one's worth reading too, for a bit of a counterbalance and as good a working definition of "deus ex machina" as any you'll see.)