It airs here tomorrow evening, so I'll let you know what I think then.
The biggest thing to bear in mind is that this is the farewell from Russel T Davies. The episodes that begin in the spring are from the new regime, with Steven Moffat in charge. This is the man who brought us "The Empty Child / The Doctor Dances", "The Girl in the Fireplace", "Blink", and "Silence in the Library / The Forest of the Dead". Not to mention Coupling. I have no worries at all that this finale is stinking up the joint, other than the fact that it is a sad way to send of David Tennant. He deserves much better.
Still, come Easter we have a brand new series from end to end, run by a guy who actually knows how to write. I'll give Russel T Davies his props, in that he did an excellent job of bringing back the series and making it relevant to a broader audience. There is no denying that he made very smart choices, particularly with the Eccleston series, that were able to sell the series to more than just the geek crowd.
But Steven Moffat truly lives and breathes Doctor Who. I have complete faith in his ability to revitalize the show and take it in some interesting new directions. This is a tectonic shift, on par with the transition from Patrick Troughton to John Pertwee, where the entire cast and production staff have changed over.
Plus, as one of my friends pointed out, it's nice to have a heterosexual male picking out the "dad candy" for the Doctor's new assistant:
"Sadly then I knew the answer. All her life she was a dancer, but no one ever played the song she knew." - The Residents