So the ninth incarnation of the Doctor leaves the stage, making way not to save mankind, the day in general or whatever else was at stake – „coward any day“ – but rather Rose, in return for having been saved by her, together with mankind et al.
All the actual saving is done by the Tardis, or by Rose, or, if you will, by her mother’s friend who happens to own a wrecker truck, depending on how you measure the individual contributions.
Bad, bad wolf, bad, bad Russell T Davies, patching the gaping holes in his plotline as he goes. The entire bad wolf scheme nothing but a reminder by the Tardis to Rose, just as seen in the TNG episode, „Cause and Effect„? The Tardis able to resolve any crisis in moments – then why ever bother to have 45 mins of hassle for each previous crisis? The most unbreakable ship opening up not to a command, not to a Mini on a chain, but yes, to the mere physical power of a wrecker truck? We are not satisfied.
And next, David Tennant. Well, we shall see.