It can be hard to make out her lyrics in some places, but this song is glorious. I love the fragments of the poem from 'The Wolfman'. I also love 'Hardest of Hearts', 'Bird Song', and 'Heavy In Your Arms', among others.
This theme is not techno, which is something I always associated with the Doctor, and so amazing. It is a heartbreaking theme for the last Billie Tyler appearance. Although Rose and the Tenth Doctor had a romantic relationship, this theme could have been applied to other intense relationships that had been ended, such as the death of a child. You definitely do not have to have seen the episode to know that the parting was not voluntary. Another great Doctor Who track, beyond the theme, is 'Bad Wolf Theme'.
available on CD - Doctor Who Original Television Soundtrack