There are laws, there are laws of time. Once upon a time there were people in charge of those laws, but they've died. They all died. Do you know who that leaves ME? It's taken me all these years to realise, the laws of time are MINE. AND THEY WILL OBEY ME!
Need I say more? I wish they'd shown us more of this darker Doctor, but the descent to this point has (rightly) taken a long time. Sometimes we saw glances of it, sometimes he let his guard down, and sometimes the disguise just completely dropped, but I'm sure we all know it was there. Hopefully RTD will man up and make the finale worthy. But then, that's why they gave us Torchwood. Because in the end the Doctor is the hero, and he's not allowed to be badass for too long lest it confuse the kids watching.
I just want to see the Valeyard snap his (very confused) assistant's neck and go do everything the Doctor tried not to. There's a late-night spinoff for you BBC :-P
On unrelated notes, I hope everyone noticed the reference in the name of the base and the one to K-9 ;-)