It was a good episode, but I think it had one major blooper
the 12th doctor's TARDIS was taken by the ship, so the two doctors used the first Doctor's TARDIS to travel to the Dalek library, all fine there, but when did they go back to recover the TARDIS? because we then see both TARDIS in space, and they didn't go back to the ship to recover the second? its like they missed a scene there.
But I would say that was fine acting from Capaldi, and yes, it is a shame we didn't see that much, otherwise, I would have rated him a lot higher. But then again, the episode was written by Steven Moffat, so that probably had something to do with it.
Overall, great episode, hopefully the new season will be good as well. [/b]