Is it very evil of me to be amused that Rose is now stuck with the version of the Doctor who would carelessly commit genocide and her mission is to reform him? Good luck with that one, sweetie.
Donna's fate was less awful than I was expecting it to be -- sure, it's sad in the same way that the ending of Silver on the Tree is sad, with the forgetting and all, but it's a better fate than being stuck in a computer matrix in a purely virtual reality, or consumed in the heart of a raging neutron drive, or even becoming absorbed into the TARDIS for all eternity. There's still the potential for Donna to grow and change as a person, and to live a happy life on her own terms -- whereas she could never have happily gone back to Earth after travelling with the Doctor for so long. She had an awesome season, she did great things, and she's still the Donna we met in The Runaway Bride only without the pain of having loved and lost her fiance to a giant red spider, which if you ask me, is all to the good.
Basically I am happy because Donna is a) still Donna and b) NOT DEAD. So yays?
Bring on the Christmas special!