First things first, I would like to make USA viewers aware of how much the Sci-Fi Channel sucks monkey butt for cutting out so many important parts of this episode. I highly recommend finding the full version of this episode online (surfthechannel.com), because you missed the following things (that I noticed, and there may be more):
-Rose telling Donna who the "little band of fighters" were on the Sontaran ship - specifically that they were Gwen Cooper, Ianto Jones and freakin' Captain Jack Harkness. You know, no big loss not knowing that detail, right.
-The explanation of why the Indian guy the Nobles were living with was being taken away, and a very emotional moment between him and Wilf that really brought home the gravity of the entire situation.
-AlternateWorld!Donna's full reaction to seeing the inside of the TARDIS for the first time. She doesn't just walk in, say "no way" and then walk back out and ask for coffee. It was a great, great character moment that we never got the first time we met her because Donna saw the inside of the TARDIS before she saw the outside. She goes in, goes out, goes in again, goes out and walks all the way around it, completely disbelieving... it was great. And they didn't show ANY OF IT.
I'm so upset that Sci-Fi butchered this episode.
But anyway, as for my actual opinions on the whole episode...
Actually, hold on. Why, exactly, does the Sci-Fi Channel make its own trailers for the show? What's wrong with the ones that play at the end of the episode on the BBC? The ones without the stupid voiceover? I think that's what I have the most trouble with - the annoying Sci-Fi guy's voiceover on the previews.
Whatever.
I loved this episode. The first time I saw it, I was completely spazzing out at the end when the Doctor found out Rose was coming back. It was the weirdest thing I've ever experienced. No TV show has ever had me crying and shaking by the end of an episode. Thank you Doctor Who for accomplishing that.
When done well, "What If?" stories are my favorite things ever, and that's what this episode was. What if Donna had never met the Doctor? What would things be like? I love the speculation of that, and how the world would compensate - or not - in his absence.
The reason the Doctor is dead is completely devastating. The UNIT officer thought he drowned too fast to regenerate, but that isn't true. In The Runaway Bride, Donna tells him to stop - without her, he doesn't, and he lets himself die. Why? Because he's just gone through a horrific ordeal with losing Rose to the sealed off parallel world, and had no desire to live. This was displayed repeatedly in series 3. For example: in the Daleks in Manhattan episode, he basically screams at a Dalek to kill him because "it's his turn." This episode added an entirely new depth to that Christmas special and the Doctor's character and state of mind at that point in the show.
I would like to point out how absolutely splendid Catherine Tate and Billie Piper are. This was the Doctor Lite episode of the season, and it's not like you didn't notice he was gone (since the whole point of the episode was what the world would be like without him, of course you noticed), but the episode didn't suffer at all for not having David Tennant running around with his hair and his grin because of these two brilliant actresses. One day, I will be friends with them. Or I'll at least somehow get my picture taken with them and frame it and put it over my desk for the rest of my life.
One last thing - the music in this episode was so wonderful. Specifically, when Donna steps into the impromptu time machine that Rose and UNIT made with what was left of the TARDIS. It was beautiful and is another example of emotional music by Murray Gold that succeeded in making me teary eyed. (Previous examples of this include the songs "Doomsday" and "This is Gallifrey: Our Childhood, Our Home" which are arguably the best songs on the first two soundtracks.)
Next week: The Stolen Earth! And thanks to the uber-revealing trailer, there's a bit of a regeneration scare coming up. Thanks for spoiling the surprise, Sci-Fi!