I seem to be going off-topic - or rather, what I was gonna talk about this time: the season finale. I did enjoy it, but first a couple of caveats:
(1) Given the scale of the previous finales, how can you top yanking the Earth out of its orbit and then towing it back? Upping the ante on the Cybermen/Dalek war in Series Two and the Master's domination of the world in Series Three took serious chutzpah on RTD's part, and I'm not surprised by his decision to leave. Poor boy's exhausted, doncha know. In retrospect, it's a good thing that the Beeb is letting the series take a breather with four specials rather than cranking out a new season.
(2) Donna's fate, IMHO, is a screwjob of the first order

. Only the notion of Superman flying around the world fast enough to reverse time rankles me more.
(3) Why carry around Implements of Mass Destruction (the Osterhagen Key, for example) if they're just going to be discarded like gumwrappers? And Doctor 10 Mk 2 and DoctorDonna running headlong into consecutive Davros zaps? Puh-and-leeeeese.
Overall, there was more to cheer for than crab about

.
(1) Mickey and Jackie coming to Sarah Jane's rescue (Jackie packing serious high-tech heat - like daughter, like mother).
(2) The nebulous nature of Davros' standing with "his" Daleks - at least that's how I think of it.
(3) The hilarious paranoid insanity of the Reality Bomb Plot. Nice of the Daleks to come up with something that suits their nature.
(4) Davros and Sarah Jane get reacquainted. "Really, Ms. Smith, we should sit down to tea and biscuits, but I've got to go EX-TER-MI-NATE everything first. Give me a call next week and...oh, sorry, you won't be here."
(5) The DoctorDonna - neatly done.
(6) Doctor 10 Mk 2 - it's always good to carry a spare.
(7) The Doctor turns the tables on his enemies - AGAIN! - but not without consequences. Back in Genesis of the Daleks, he pondered the question of genocide. This time, he answered it, and no doubt the result is going to stay with him for a while.
(8) Our happy band pilot the TARDIS with the Earth in tow - one of the more joyous images in science fiction of note.
(9) K-9 pops up!

Now let's hope someone decides to get the legalese sorted so he can be a regular on The Sarah Jane Adventures (awesome spin-off, by the by).
(10) Goodbyes are sad occasions, but they can be especially touching (Pretty Lady on Terminus comes to mind). It's nice to see the Doctor and his secret family achieve closure (even though I thought Donna got the shaft).