Wow. What a set-up for what looks like being a storming finale. I was on the edge of my seat for the whole of this episode, right up until the enormous shock at the end and its subsequent cliffhanger. Quite often the plots of the finale are quite hard to keep up with, but that's certainly not the case here.
Russell T Davies, with his script for this episode, has somehow managed to intertwine his entire "Whoniverse" together. Not just with the characters - all the favourites are back (Jack, Martha, Sarah Jane, and of course, Rose - and even Harriet Jones makes an important cameo) along with the two spin-offs Torchwood and The Sarah Jane Adventures (with Gwen and Ianto from the former and Luke from the latter playing large parts), but also, just like with The Sound of Drums last year, all the seemingly insignificant events from earlier episodes that you dismissed as part of those story lines alone have become massive plot developments. It's obvious just how much careful planning Davies has put into this entire series on the first watch of this. On top of this, we finally discover what the Medusa Cascade and the Shadow Proclamation (complete with random Judoon cameo) are - things that have been talked about ever since Christopher Eccleston's first episode.
Even things that I would normally criticise serve this episode very well. The main thing being Murray Gold's repetitive music - he's borrowed music from all over the rest of the series for this episode and yet it still works really well.
As for the acting, I don't think there was a single bad performance. John Barrowman and Elisabeth Sladen in particular are on top form, Tennant is excellent as always, and Julian Bleach's Davros is frighteningly reminiscent of Star Wars' Emperor Palpatine. And from the trailer that has just appeared on the BBC website, it's only going to get better.
Again, what an amazing setup for next week's finale, and a very convincing episode in its own right. And so begins the anticipation...