Firstly, let's get the most important thing out of the way - it was good. The first 30 seconds or so, before it all goes a bit adventurey, are a pleasing link from the very first episode to present day, and the last shot of the episode - without wanting to give anything away - is a nice way to round off the first 50 years of the show.
In between those opening and closing shots, there's 75 minutes of spectacle with a plot that, at least as far as I can tell, holds up to scrutiny better than many recent episodes of the series itself.
The feature-length piece also, of course, INTRODUCES JOHN HURT AS THE DOCTOR, but the lack of subtlety with which he was shoutily announced at the end of the preceding episode has been smoothed out slightly, and he fills the role nicely without stealing the show as the biggest 'name' among the cast members.
Subtlety is, for once, to be found in abundance in The Day of the Doctor, which manages simultaneously to give a nod to the classic era of the show, the early days of its modern-era revival and its current incarnation with Matt Smith at the helm of the TARDIS and of the show.
Billie Piper's appearance (again, hardly a spoiler by the time you've watched the opening credits) is handled well, allowing her to feature without getting bogged down in the Tenth Doctor/Rose storyline - which, remember, younger newcomers to the show may not have seen.
And there's a curious Wizard of Oz undercurrent throughout - look out for the ruby slippers in the Black Vault, Clara (IIRC) calling herself the 'Wicked Witch of the West' and Ingrid Oliver's character name 'Osgood' (Clara is, of course, varyingly known as Clara Oswald or simply as Oswin in previous episodes).
I've been trying to work out if the three Doctors are meant to represent the Scarecrow (Smith), Tin Man (Tennant) and Cowardly Lion (Hurt), but it's not a perfect fit - maybe it's all just my imagination.
I could spell out all of the references to the earlier Doctors, but I won't - I'll leave that for somebody far more familiar with the show than I am, and for a page that's less careful about spoilers.
But needless to say, as a viewer who came to the show in the mid to late 1980s (I wasn't born until 1983, so I like to think I have an excuse), there was enough of the spirit of Doctor Who as I knew it then, balanced nicely with the modern-day sense of the show as the new generation of fans have come to know it - not to mention a couple of surprises thrown in purely for the older fans, which seems fitting for an anniversary of such magnitude.
I do wonder how they got from the end of the previous episode to the beginning of this story, but perhaps that doesn't matter too much - it really needed to stand alone, so viewers who tuned in only for the anniversary did not feel lost from the outset, and I suspect it achieved that aim fairly well.
The focus now has to be on Peter Capaldi - it's no secret that this year's Christmas special is likely to see Matt Smith bow out and regenerate, which will ruin Christmas Day for a few kids, but never mind.
Can Capaldi continue to unite the two eras of Doctor Who? Restore The Doctor to his true, original character as a grumpy grown-up, rather than a clown? Bring back the darker side of the character and the show, for a generation of fans who came to the show as adolescents but are now reaching maturity in their own right?
I had all but written off Doctor Who until this anniversary episode; now I greet the oncoming storm with optimism. I have loved Matt Smith but, like Sylvester McCoy, he has rarely had the storylines he needed to shine to his fullest potential. Bring on Capaldi.
