The point of 'Doomsday' was to write out Rose. I've thought before that Davies recognises that a lot of the programme's appeal has rested in its startling images - unsurprising, I'd say, from someone whose first childhood memories of the programme are I think from when Innes Lloyd was producer - and RTD has confirmed that the starting point of the 'Army of Ghosts'/'Doomsday' two-parter was a mental image of a room with two big levers in it - one for the Doctor, and one for Rose.
As an admirer of Philip Pullman's work - and appropriate considering what Billie Piper is going on to do - I liked the homages throughout this episode to His Dark Materials. The Doctor's 3D glasses were his amber spyglass, revealing the 'dust' of voidstuff; and while the voidstuff didn't confirm self-awareness and independence like Pullman's dust, there is no doubt that the central human characters have all changed during the past two years. Wealth, power and loss have brought Pete responsibility tempered in the end with humility, necessary to accept Rose as 'his' daughter, as happens when he returns for her just before Rose is sucked into the void.
The detail of the Doctor's relationship with Rose has for the most part been ignored; we've instead largely seen them enjoying each other's company and being smug and avoiding the questions brought up by 'School Reunion'. In hindsight this looks like denial, Rose realising that her relationship with the Doctor is not unique (and she should have kept in mind the ease with which he bonded with Lynda-with-a-Y in 'Bad Wolf'/'The Parting of the Ways') leading to her resolving that she should be the exception; and the Doctor not wanting to let her down even though he knows, really, that the time would come when he would have to make the decision for both of them. David Tennant played the ambiguities of the Doctor's final scenes with Rose very well; there was a slight suggestion of resentment that Rose had found her way back to our universe to close the breach, which did not compromise his agony at their parting.
These few paragraphs have taken far too long to write; but I'll wrap up for now that I'm mystified both by the faults found in these episodes by many online fans and at the rejection of Catherine Tate; there's a distinction between her comic personae (of which I've seen very little) and the actress, and I'm looking forward to a Christmas special co-starring one of the BBC's rising female leads as the temporary companion.