Although not physically unwatchable, I have voted as such because staring at a blank wall would have been a better utilisation of my time.
A few things which regrettably have clung to my mind after over a week:
RTD has no sense of scale; 25 nukes can blow up the planet? Aye right.
Donna saying a bunch of random words destroyed the Daleks. I'm confused; is Doctor Who meant to be science fiction or fantasy?
The last 15 or 20 minutes seemed completely superfluous. The whole saying goodbye thing could have been easily compressed into 2 or 3 minutes as opposed to drawing it out into something which was most of the reason this episode was over an hour long.
Why was the Earth the last planet left? What purpose did that serve? It hardly served as a problem at all.
Probably more, but none which can come to mind right now.
Oh, also, hi, I'm back.