I quite enjoyed the episode, especially seeing as I watched it from the jacuzzi in the room with a takeaway pizza and garlic bread next to me.
That was quite a stunning revelation to me, that Jack is the Face of Boe, that was kinda weird, though it does explain how he had enough life enegy to sustain the entire planet earlier in the season, but not how he was apparently the "last of his kind" when there were other humans still alive.